Warrantless Cellphone Tracking Is Upheld

The closely watched case, in the United States Court of Appeals for the Fifth Circuit, is the first ruling that squarely addresses the constitutionality of warrantless searches of historical location data stored by cellphone service providers. Ruling 2 to 1, the court said a warrantless search was “not per se unconstitutional” because location data was “clearly a business record” and therefore not protected by the Fourth Amendment.

The ruling is likely to intensify legislative efforts, already bubbling in Congress and in the states, to consider measures to require warrants based on probable cause to obtain cellphone location data.

The appeals court ruling sharply contrasts with a New Jersey State Supreme Court opinion in mid-July that said the police required a warrant to track a suspect’s whereabouts in real time. That decision relied on the New Jersey Constitution, whereas the ruling Tuesday in the Fifth Circuit was made on the basis of the federal Constitution.

The Supreme Court has yet to weigh in on whether cellphone location data is protected by the Constitution. The case, which was initially brought in Texas, is not expected to go to the Supreme Court because it is “ex parte,” or filed by only one party — in this case, the government.

But the case could renew calls for the highest court to look at the issue, if another federal court rules differently on the same question. And two other federal cases involving this issue are pending.

“The opinion is clear that the government can access cell site records without Fourth Amendment oversight,” said Orin Kerr, a constitutional law scholar at George Washington University Law School who filed an amicus brief in the case.

For now, the ruling sets an important precedent: It allows law enforcement officials in the Fifth Circuit to chronicle the whereabouts of an American with a court order that falls short of a search warrant based on probable cause.

“This decision is a big deal,” said Catherine Crump, a lawyer with the American Civil Liberties Union. “It’s a big deal and a big blow to Americans’ privacy rights.”

The group reviewed records from more than 200 local police departments last year, concluding that the demand for cellphone location data had led some cellphone companies to develop “surveillance fees” to enable police to track suspects.

In reaching its decision on Tuesday, the federal appeals court went on to agree with the government’s contention that consumers knowingly give up their location information to the telecommunications carrier every time they make a call or send a text message on their cellphones.

“That means it is not protected by Fourth Amendment when the government goes to a third-party service provider and issues something that is not a warrant to demand production of those records,” said Mark Eckenwiler, a former Justice Department lawyer who worked on the case and is now with the Washington law firm Perkins Coie. “On this kind of historical cell site information, this is the first one to address the core constitutional question.”

Historical location data is crucial to law enforcement officials. Mr. Eckenwiler offered the example of drug investigations: A cellphone carrier can establish where a suspect met his supplier and how often he returned to a particular location. Likewise, location data can be vital in establishing people’s habits and preferences, including whether they worship at a church or mosque or whether they are present at a political protest, which is why, civil liberties advocates say, it should be accorded the highest privileges of privacy protection.

The decision could also bear implications for other government efforts to collect vast amounts of so-called metadata, under the argument that it constitutes “business records,” as in the National Security Agency’s collection of Verizon phone records for millions of Americans.

“It provides support for the government’s view that that procedure is constitutional, obtaining Verizon call records, because it holds that records are business records,” said Mr. Kerr, of George Washington University. “It doesn’t make it a slam dunk but it makes a good case for the government to argue that position.”

An important element in Tuesday’s ruling is the court’s presumption of what consumers should know about the way cellphone technology works. “A cell service subscriber, like a telephone user, understands that his cellphone must send a signal to a nearby cell tower in order to wirelessly connect his call,” the court ruled, going on to note that “contractual terms of service and providers’ privacy policies expressly state that a provider uses a subscriber’s location information to route his cellphone calls.”

In any event, the court added, the use of cellphones “is entirely voluntary.”

The ruling also gave a nod to the way in which fast-moving technological advances have challenged age-old laws on privacy. Consumers today may want privacy over location records, the court acknowledged: “But the recourse for these desires is in the market or the political process: in demanding that service providers do away with such records (or anonymize them) or in lobbying elected representatives to enact statutory protections.”

Cellphone privacy measures have been proposed in the Senate and House that would require law enforcement agents to obtain search warrants before prying open location records. Montana recently became the first state to require a warrant for location data. Maine soon followed. California passed a similar measure last year but Gov. Jerry Brown, a Democrat, vetoed it, saying it did not strike what he called the right balance between the demands of civil libertarians and the police.

Bits Blog: A Digital Diaper for Tracking Children’s Health

A screen shot from Pixie Scientific’s Web site, showing its diapers and accompanying smartphone app that can transmit certain health information to a physician.

Talk about changing with the times.

A New York start-up called Pixie Scientific has developed a diaper that the company says can detect possible urinary tract infections, kidney dysfunctions, and dehydration, accompanied by a smartphone app that can transmit the information to a physician.

“I was driving with my wife and daughter one day, when my wife asked if the baby had wet herself,” said Yaroslav Faybishenko, Pixie’s founder. “I realized she was sitting in data.”

Other so-called quantified self products have been developed for adults, like products from Jawbone and FitBit that create digital records of calorie expenditure and sleep habits. At this year’s Consumer Electronics Show, a Taiwanese company called AiQ showed off shirts that it said could measure things like heart rate and other biometric signals.

In contrast to those things, the technology behind the diaper is relatively simple, and it owes as much to the quality of smartphone cameras as it does to clever chemistry.

At the front of the diaper is a patch with several colored squares. Each square represents a different interaction with a protein, water content or bacteria, and changes color if it detects something is outside of normal parameters. There is also a neutral white square, to more easily check for color changes in the other squares.

A smartphone app takes a picture and can make precise readings of the chemical data based on  color changes. The data is uploaded to a central location, where physicians can get information about how the child is doing and whether the baby needs further testing.

The diaper is expected to be tested at Benioff Children’s Hospital of the University of California, San Francisco this September. Columbia University’s children’s hospital is considering a similar study. If successful, the product may then be submitted to the Food and Drug Administration for final approval.

Mr. Faybishenko said he thought the diaper, which he said would cost about 30 percent more than regular diapers, had potential as a consumer product, for parents who want to keep regular tabs on their child’s health. Rather than overwhelming parents with data, the app is likely to let them know whether they should see a pediatrician for one or more possible conditions. With the parents’ permission, the detailed urine analysis data could be sent to a doctor’s office.

“You really don’t want to overload parents with data they don’t understand,” he said. “Eventually the quantified self idea will be mostly silent and unobtrusive, just something inside the existing flow of life.”

Mr. Faybishenko said the company was working on other tests, but would not specify what they were.

Devices Given to Chinese Legal Advocate Had Tracking Spyware, N.Y.U. Says

But according to officials at New York University, several electronic devices that were given to Chen Guangcheng, a Chinese legal advocate, soon after his arrival in the United States last year were loaded with spyware designed to track his family’s movements and their online activity.

Two of those devices, an iPhone and an iPad, were given to Mr. Chen by China Aid, a Texas-based Christian group that pushes for greater religious freedom in China. Bob Fu, the president of the group, said that he was out of the country when Mr. Chen arrived in New York so his wife, Heidi, handed over the equipment. The discovery of the tracking software came as a complete surprise, he said.

“This story is just crazy,” said Mr. Fu, an exiled Chinese dissident who championed Mr. Chen’s plight during the years of persecution Mr. Chen endured as an opponent of forced abortion.

The allegations, first reported by Reuters, threatened to further complicate an already messy narrative surrounding Mr. Chen’s tenure at N.Y.U., which includes accusations that school officials, bowing to pressure from the Chinese government, sought to curtail his public advocacy and then forced him to leave the Greenwich Village campus sooner than he expected.

School officials and associates of Mr. Chen, who is blind, have vehemently rejected such assertions and insisted that his fellowship at N.Y.U. was always meant to last one year.

Mr. Chen has declined to provide evidence backing up his assertions, issued in a brief statement last Sunday, that Beijing pressured N.Y.U. to terminate what he acknowledged was a generous arrangement that included tutors, security and housing for him, his wife, and their two children.

With Mr. Chen silent in recent days, Mr. Fu has become one of his more vocal advocates, eagerly telling reporters what Mr. Fu said were instances in which N.Y.U. tried to limit Mr. Chen’s access to conservative political figures and advocates who opposed abortion. Representative Christopher H. Smith, Republican of New Jersey, who frequently confers with Mr. Fu on human rights issues in China, has threatened to convene a Congressional hearing on Mr. Chen’s time at N.Y.U.

According to people with knowledge of the episode, Mr. Fu’s wife presented the Apple devices to an assistant of Jerome Cohen, the N.Y.U. law professor who was instrumental in arranging Mr. Chen’s exit from the American Embassy in Beijing, where he had sought refuge after escaping house arrest.

The gifts, along with at least two other phones that were handed to the assistant, arrived on the chaotic day Mr. Chen and his family landed in New York. After an examination by N.Y.U. technicians, all the devices were found to be compromised with spyware, said an associate, who asked to remain anonymous because he was not authorized to speak to the news media.

The spyware included global positioning software that allowed a third party to track the whereabouts of the device, and presumably its owner, and another program that copied its contents to a remote server. After removing the spyware, technicians returned the Apple devices to the Chens, who were told about what had happened. The two other phones, their provenance a mystery, were not given to Mr. Chen.

“He was upset, but he was more concerned about the relatives he left behind who were being mistreated by the authorities,” the associate said.

Mr. Fu was not informed about the spyware on the items, and by all accounts, his relationship with the family deepened in the months that followed.

John H. Beckman, an N.Y.U. spokesman, confirmed the broad outlines of the episode but said he had no further information. Professor Cohen told Reuters he thought the compromised devices were an attempt to keep tabs on Mr. Chen remotely. “These people supposedly were out to help him, and they give him a kind of Trojan horse that would have enabled them to monitor his communications secretly,” he said.

Professor Cohen was traveling in Asia on Friday and could not be reached for comment.

In an interview, Mr. Fu said he learned on Thursday from Reuters that the items his wife had bought at an AT&T store in Texas were compromised. He said a technician he employs had activated the devices and added Skype but nothing else.

He suggested that the spyware could have been installed after his wife dropped off the items but before they were given to the Chens, a gap of at least a day.

“More than anyone else, we want to get to the bottom of this,” he said, adding that he had asked the F.B.I. to look into the matter. “We will fully cooperate with any investigation and hope N.Y.U. will do the same.”

Devices Given to Chinese Legal Advocate Had Tracking Spyware, N.Y.U. Says

But according to officials at New York University, several electronic devices that were given to Chen Guangcheng, a Chinese legal advocate, soon after his arrival in the United States last year were loaded with spyware designed to track his family’s movements and their online activity.

Two of those devices, an iPhone and an iPad, were given to Mr. Chen by China Aid, a Texas-based Christian group that pushes for greater religious freedom in China. Bob Fu, the president of the group, said that he was out of the country when Mr. Chen arrived in New York so his wife, Heidi, handed over the equipment. The discovery of the tracking software came as a complete surprise, he said.

“This story is just crazy,” said Mr. Fu, an exiled Chinese dissident who championed Mr. Chen’s plight during the years of persecution Mr. Chen endured as an opponent of forced abortion.

The allegations, first reported by Reuters, threatened to further complicate an already messy narrative surrounding Mr. Chen’s tenure at N.Y.U., which includes accusations that school officials, bowing to pressure from the Chinese government, sought to curtail his public advocacy and then forced him to leave the Greenwich Village campus sooner than he expected.

School officials and associates of Mr. Chen, who is blind, have vehemently rejected such assertions and insisted that his fellowship at N.Y.U. was always meant to last one year.

Mr. Chen has declined to provide evidence backing up his assertions, issued in a brief statement last Sunday, that Beijing pressured N.Y.U. to terminate what he acknowledged was a generous arrangement that included tutors, security and housing for him, his wife, and their two children.

With Mr. Chen silent in recent days, Mr. Fu has become one of his more vocal advocates, eagerly telling reporters what Mr. Fu said were instances in which N.Y.U. tried to limit Mr. Chen’s access to conservative political figures and advocates who opposed abortion. Representative Christopher H. Smith, Republican of New Jersey, who frequently confers with Mr. Fu on human rights issues in China, has threatened to convene a Congressional hearing on Mr. Chen’s time at N.Y.U.

According to people with knowledge of the episode, Mr. Fu’s wife presented the Apple devices to an assistant of Jerome Cohen, the N.Y.U. law professor who was instrumental in arranging Mr. Chen’s exit from the American Embassy in Beijing, where he had sought refuge after escaping house arrest.

The gifts, along with at least two other phones that were handed to the assistant, arrived on the chaotic day Mr. Chen and his family landed in New York. After an examination by N.Y.U. technicians, all the devices were found to be compromised with spyware, said an associate, who asked to remain anonymous because he was not authorized to speak to the news media.

The spyware included global positioning software that allowed a third party to track the whereabouts of the device, and presumably its owner, and another program that copied its contents to a remote server. After removing the spyware, technicians returned the Apple devices to the Chens, who were told about what had happened. The two other phones, their provenance a mystery, were not given to Mr. Chen.

“He was upset, but he was more concerned about the relatives he left behind who were being mistreated by the authorities,” the associate said.

Mr. Fu was not informed about the spyware on the items, and by all accounts, his relationship with the family deepened in the months that followed.

John H. Beckman, an N.Y.U. spokesman, confirmed the broad outlines of the episode but said he had no further information. Professor Cohen told Reuters he thought the compromised devices were an attempt to keep tabs on Mr. Chen remotely. “These people supposedly were out to help him, and they give him a kind of Trojan horse that would have enabled them to monitor his communications secretly,” he said.

Professor Cohen was traveling in Asia on Friday and could not be reached for comment.

In an interview, Mr. Fu said he learned on Thursday from Reuters that the items his wife had bought at an AT&T store in Texas were compromised. He said a technician he employs had activated the devices and added Skype but nothing else.

He suggested that the spyware could have been installed after his wife dropped off the items but before they were given to the Chens, a gap of at least a day.

“More than anyone else, we want to get to the bottom of this,” he said, adding that he had asked the F.B.I. to look into the matter. “We will fully cooperate with any investigation and hope N.Y.U. will do the same.”

Bits: Technology Turns to Tracking People Offline

Following people online, with cookies, tagged pixels and even voluntarily given information, has been a big business. Now much of the same technology is moving into the physical world.

A company called Euclid Analytics uses the Wi-Fi antennas inside stores to see how many people are coming into a store, how long they stay and even which aisles they walk. It does this by noting each smartphone that comes near the store, feeding on every signal ping the phone sends.

“Three years ago, I went to the Stanford mall in Palo Alto and could count about 30 percent of the people there” by listening for Wi-Fi signals, says Will Smith, the company’s chief executive. “Now in San Francisco, it’s about 60 percent. In Atlanta or Charlotte, it’s 40 percent.”

Karsten Moran for The New York Times Customers in Home Depot, one of the companies working with Euclid Analytics to use Wi-Fi to learn about customer behavior.

Using the information, retailers can tell whether someone walked by the store, whether a customer came in and how long the visit lasted. If it is a big store, with a couple of Wi-Fi antennas, the owner can start to see where in the store someone went.

Euclid is three years old and has about 100 customers, including Nordstrom and Home Depot. It has already tracked about 50 million devices in 4,000 locations.

The big initial use is the so-called bounce rate, or the percentage of people who come into the store who leave without making a purchase. But the technology also helps stores make sure that there is enough sales help or that enough registers are open. By seeing how people move in a store, retailers can also better determine where to place low-profit and high-profit items.

Mr. Smith says Euclid has more data than it gives to customers. It gives its customers only anonymous data in a collected form, so individuals won’t be targeted. Stores using the technology may also put stickers in their windows telling customers they are being monitored and allowing them to opt out

It’s likely, however, that over time Euclid and its partners could add an opt in feature, where people choose to be recognized, the way registered Amazon.com customers are greeted when they come to a site. Then people might be offered, say, free parking for staying 20 minutes in a store, or they could get a discount for visiting three times a month.

Computers are already recognizing people moving around, both voluntarily and involuntarily. Mr. Smith was talking about his company at a conference in Santa Monica, Calif., held by the Montgomery & Company investment firm. Down the hall, a company called Omnilink, which makes ankle devices for people under home arrest, talked about plans to expand into monitoring elders, children, workers on their own in the field and the infirm.

“Personal tracking is burgeoning,” said Kelly Gay, Omnilink’s chief executive. “It only takes one child to go missing or one person falling off a wall for us to see growth.” The company has just started moving away from judicial monitoring, but it is seeing quick results: It tracks about 15,000 people on the judicial side (a very profitable business, with revenue of $140 a month a user), and it has 35,000 people who are voluntarily tracked.

Both are likely to increase, Ms. Gay says. On one side, prison overcrowding and tight budgets make it likely that more felons will do time outside the walls. On the personal side, the aging baby boom population makes it likely that there will be an increase in dementia, so people will require more monitoring.

But who needs ankle monitors when you have a smartphone? Ms. Gay’s presentation was well received. Mr. Smith was mobbed with bankers willing to lend him money and entrepreneurs wanting to work with his monitoring business.

Slipstream: Legislation Would Regulate Tracking of Cellphone Users

THERE are three things that matter in consumer data collection: location, location, location.

E-ZPasses clock the routes we drive. Metro passes register the subway stations we enter. A.T.M.’s record where and when we get cash. Not to mention the credit and debit card transactions that map our trajectories in comprehensive detail — the stores, restaurants and gas stations we frequent; the hotels and health clubs we patronize.

Each of these represents a kind of knowing trade, a conscious consumer submission to surveillance for the sake of convenience.

But now legislators, regulators, advocacy groups and marketers are squaring off over newer technology: smartphones and mobile apps that can continuously record and share people’s precise movements. At issue is whether consumers are unwittingly acquiescing to pervasive tracking just for the sake of having mobile amenities like calendar, game or weather apps.

For Senator Al Franken, the Minnesota Democrat, the potential hazard is that by compiling location patterns over time, companies could create an intimate portrait of a person’s familial and professional associations, political and religious beliefs, even health status. To give consumers some say in the surveillance, Mr. Franken has been working on a locational privacy protection bill that would require entities like app developers to obtain explicit one-time consent from users before recording the locations of their mobile devices. It would prohibit stalking apps — programs that allow one person to track another person’s whereabouts surreptitiously.

The bill, approved last month by the Senate Judiciary Committee, would also require mobile services to disclose the names of the advertising networks or other third parties with which they share consumers’ locations.

“Someone who has this information doesn’t just know where you live,” Mr. Franken said during the Judiciary Committee meeting. “They know the roads you take to work, where you drop your kids off at school, the church you attend and the doctors that you visit.”

Yet many marketers say they need to know consumers’ precise locations so they can show relevant mobile ads or coupons at the very moment a person is in or near a store. Informing such users about each and every ad network or analytics company that tracks their locations could hinder that hyperlocal marketing, they say, because it could require a new consent notice to appear every time someone opened an app.

“Consumers would revolt if this was the case, and applications could be rendered useless,” said Senator Charles Grassley, the Iowa Republican, who promulgated industry arguments during the committee meeting. “Worse yet, free applications that rely on advertising could be pushed by the consent requirement to become fee-based.”

Mr. Franken’s bill may seem intended simply to protect consumer privacy. But the underlying issue is the future of consumer data property rights — the question of who actually owns the information generated by a person who uses a digital device and whether using that property without explicit authorization constitutes trespassing.

In common law, a property intrusion is known as “trespass to chattels.” The Supreme Court invoked the legal concept last January in United States v. Jones, in which it ruled that the government had violated the Fourth Amendment — which protects people against unreasonable search and seizure — by placing a GPS tracking device on a suspect’s car for 28 days without getting a warrant.

Some advocacy groups view location tracking by mobile apps and ad networks as a parallel, warrantless commercial intrusion. To these groups, Mr. Franken’s bill suggests that consumers may eventually gain some rights over their own digital footprints.

“People don’t think about how they broadcast their locations all the time when they carry their phones. The law is just starting to catch up and think about how to treat this,” says Marcia Hofmann, a senior staff lawyer at the Electronic Frontier Foundation, a digital rights group based in San Francisco. “In an ideal world, users would be able to share the information they want and not share the information they don’t want and have more control over how it is used.”

Even some marketers agree.

One is Scout Advertising, a location-based mobile ad service that promises to help advertisers pinpoint the whereabouts of potential customers within 100 meters. The service, previously known as ThinkNear and recently acquired by Telenav, a personalized navigation service, works by determining a person’s location; figuring out whether that place is a home or a store, a health club or a sports stadium; analyzing weather and other local conditions; and then showing a mobile ad tailored to the situation.

Eli Portnoy, general manager of Scout Advertising, calls the technique “situational targeting.” He says Crunch, the fitness center chain, used the service to show mobile ads to people within three miles of a Crunch gym on rainy mornings. The ad said: “Seven-day pass. Run on a treadmill, not in the rain.”

When a person clicks on one of these ads, Mr. Portnoy says, a browser-based map pops up with turn-by-turn directions to the nearest location. Through GPS tracking, Scout Advertising can tell when someone starts driving and whether that person arrives at the site.

Despite the tracking, Mr. Portnoy describes his company’s mobile ads as protective of privacy because the service works only with sites or apps that obtain consent to use people’s locations. Scout Advertising, he adds, does not compile data on individuals’ whereabouts over time.

Still, he says, if Congress were to enact Mr. Franken’s location privacy bill as written, it “would be a little challenging” for the industry to carry out, because of the number and variety of companies involved in mobile marketing.

“We are in favor of more privacy,” Mr. Portnoy says, “but it has to be done within the nuances of how mobile advertising works so it can scale.”

A SPOKESMAN for Mr. Franken said the senator planned to reintroduce the bill in the new Congress. It is one of several continuing government efforts to develop some baseline consumer data rights.

“New technology may provide increased convenience or security at the expense of privacy and many people may find the trade-off worthwhile,” Justice Samuel Alito wrote last year in his opinion in the Jones case. “On the other hand,” he added, “concern about new intrusions on privacy may spur the enactment of legislation to protect against these intrusions.”

E-mail: slipstream@nytimes.com.

Gadgetwise Blog: App City: Tracking the Election

Digital tools are being used in myriad ways in 2012. The Obama campaign created a smartphone app to help volunteers canvass. Two clever apps will listen to political ads and give users information about the organizations that paid for them: Ad Hawk, by the Sunlight Foundation, a nonpartisan nonprofit organization that uses the Internet to promote government transparency, and Super PAC App by Glassy Media, an offshoot of the M.I.T. Media Lab.

For $1, Presidential Election Race 2012 will allow people to obsess over political polls and prediction markets. And this is to say nothing of the election news apps that The New York Times and other publications have created.

Just in time for Election Day comes Vote Planner, a Web app also from the Sunlight Foundation that is to go live on Monday. It is designed to help voters with decision-making up and down the ballot, not just in the presidential race.

Log on by entering your address into the site, and you are presented with a list of the choices on your ballot. (The site does not show what the ballot will actually look like, however.) The site also shows contributions the candidates have received, broken down by industry, and endorsements from dozens of local and national groups. (Sunlight primarily focused on gathering the opinions of local groups in New York and San Francisco for this election cycle.) The information extends from the presidential race to state legislative contests.

You can create a voting plan and publish it to a link that you can share with others or e-mail to yourself. By linking the app to a Facebook, Twitter or Google Plus account, you share whom you have selected for each race, and you get to see whom your friends are voting for. The idea is that voters who publicize their choices will encourage other people to vote, and there is some evidence that peer pressure on social media makes a difference: A study published last month by the journal Nature found that a special “get out the vote” message on Facebook had a demonstrable impact on voter turnout.

If you are not interested in sharing, do not link to a social media account. Your choices are public immediately, even if you have not clicked “publish.”

According to the Sunlight Foundation, the tool was initially envisioned as a mobile guide that voters could bring into the booth with them. But deadlines caught up with the developers, and Vote Planner exists only as a Web site that works best on a standard Web browser or a tablet, rather than a mobile phone.

It also seems strange that Vote Planner does not tell people where to vote, even though that was part of Google’s Civic Information A.P.I., or application programming interface, which Sunlight used to create its project.

Vote Planner is not the only project to use the A.P.I., however; it is open to any developer who wants to build an app with it. Google is also working with the Pew Center on the States and public officials on the Voting Information Project, which is creating a number of Web apps to help people monitor the voting process.

But maybe you are looking for less information about politics, not more. There is a technological solution for that as well. Unpolitic.me, an extension for Google’s Chrome Web browser, will block all political updates from your Twitter and Facebook feeds and replace them with pictures of cats.

Have a favorite New York City app? Send tips via e-mail to appcity@nytimes.com or via Twitter to @joshuabrustein.

Tracking Voters’ Clicks Online to Try to Sway Them

Then, as he visited other Web sites, he started seeing advertisements asking him to donate to Mitt Romney’s campaign. One mentioned family values, he said, and seemed aimed at someone with more conservative leanings.

“It doesn’t make any sense,” Mr. Goddard said. “I’m the opposite of a Romney supporter. But ever since I went to the Romney site, they’ve been following me.”

One of the hallmarks of this campaign is the use of increasingly sophisticated — but not always accurate — data-mining techniques to customize ads for voters based on the digital trails they leave as they visit Internet sites.

It is a practice pioneered by online retailers who work with third-party information resellers to create detailed portraits of consumers, all the better to show them relevant marketing pitches. Mr. Goddard, for example, may have received those Romney ads because of “retargeting” software designed to show people ads for certain sites or products they have previously viewed.

Now, in the election’s final weeks, both presidential campaigns have drastically increased their use of such third-party surveillance engines, according to Evidon, a company that helps businesses and consumers monitor and control third-party tracking software.

Over the month of September, Evidon identified 76 different tracking programs on barackobama.com — two more trackers than it found on Best Buy’s Web site — compared with 53 in May. It found 40 different trackers on mittromney.com last month, compared with 25 in May.

The report provides a rare glimpse into the number of third-party tracking programs that are operating on the campaign Web sites — as many as or more than on some of the most popular retailers’ sites.

The campaigns directly hire some companies, like ad agencies or data management firms, that marry information collected about voters on a campaign site with data about them from other sources. But these entities, in turn, may bring their own software partners to the sites to perform data-mining activities like retargeting voters or tracking the political links they share with their social networks.

Now some consumer advocates say the proliferation of these trackers raises the risk that information about millions of people’s political beliefs could spread to dozens of business-to-business companies whose names many voters have never even heard. There is growing concern that the campaigns or third-party trackers may later use that voter data for purposes the public never imagined, like excluding someone from a job offer based on his or her past political affiliations.

“Is the data going to be sold to marketers or shared with other campaigns?” said Christopher Calabrese, the legislative counsel for privacy-related issues at the American Civil Liberties Union. “We simply don’t know how this information is going to be used in the future and where it is going to end up.”

Evidon offers a free software program called Ghostery that people can use to identify third-party trackers on the sites they visit. On Oct. 18 the program identified 19 different trackers on the Obama Web site and 12 on the Romney site. A reporter contacted 10 for comment.

Among those who responded, Cassie Piercey, a spokeswoman for ValueClick, whose MediaPlex marketing analytics division was identified as operating on the Obama site by Ghostery, said she could not comment on specific clients and referred a reporter to the company’s privacy policy. The policy says that ValueClick may collect information about users — like their Internet Protocol addresses, Web browsing histories, online purchases and searches — that does not involve identifiable information like their names, and that the company may share that data with its clients and marketing partners.

Adam Berke, the president of AdRoll, an advertising and retargeting company identified by Evidon on the Obama site, said the company did not aggregate user data or share it with other clients.

Meanwhile, Nanda Kishore, the chief technology officer of ShareThis, a service found on the Romney site by Ghostery that collects information about the links visitors share with their social networks, said the company collects only “anonymous” information about users and does not share or sell it.

The privacy policies on the campaigns’ Web sites acknowledge that they work with third parties that may collect user data.

Evidon executives said the tracking companies on the campaign sites included services that collect details about people’s online behavior in order to help mold ads to their political concerns; advertising networks that track people’s browsing history to measure the effectiveness of ads; and companies that record user behavior so they can analyze the effectiveness of sites to attract and hold on to Web traffic.

Officials with both campaigns emphasize that such data collection is “anonymous” because third-party companies use code numbers, not real names, to track site visitors.

Gadgetwise Blog: Tracking Loved Ones on the Grid

So the other day, I slipped a GPS tracking device into my wife’s car before she headed off to work. I put another tracker in my 2-year-old’s diaper bag and sent him off to the nanny for the day. I still had a few trackers left, and my parents were in town, so I also threw one into their vehicle while they took my son out to the park.

Of course, I had never suspected any wrongdoing and, later on, when I reviewed the trails left by these GPS devices, they turned up nothing untoward. My spying was meant only as an experiment, but I still felt like a heel.

As well I should have. It’s precisely because of mischief like mine that tracking devices get a bad rap. These small gadgets work by connecting to GPS satellites and cellular networks to follow subjects and report back their locations to their masters. Once I sent them out into the world, I could look up the trackers online, either on the Web or through a smartphone app. They could also be configured to send me alerts based on various criteria. If my wife’s car left her office parking lot during the day or my parents’ vehicle broke the speed limit, I might get a text alert. If your mind reels at the universe of Maury Povichian possibilities contained within these gadgets, you’re not alone.

Yet after chatting with representatives at several GPS tracking companies and trying out their products, I learned that there are many less icky, entirely defensible uses for such devices. For example, some parents use trackers to make sure their children get to school and back safely each day. Others build them into their teenage drivers’ cars so they can be alerted if the kids drive recklessly. There’s also the elder-care market — GPS trackers embedded into medical-alert devices can help locate and provide emergency help for parents with Alzheimer’s.

And don’t forget the dog: a tracker attached to its collar can let you know if it wanders out of your yard, and help you find it if it doesn’t come back. The more I heard about these devices’ applications, the less unseemly they began to feel; indeed, for many people, GPS tracking could soon become a regular part of life.

Among the companies pushing for this future is Amber Alert GPS, a Utah-based firm that was founded in 2007 after Russell Thornton, a businessman, lost his 3-year-old son at an amusement park. After a frantic 45-minute search, Mr. Thornton found the boy hiding in a play structure, but he was traumatized by the incident, and it spurred him to build a device that would help other parents avoid that fate.

Amber Alert’s tracker is about the size of a child’s palm, and it looks a bit like an old-school pager. It can be slipped into a pocket or backpack, or placed in a carrying case attached to a child’s belt loop. According to Carol Colombo, the chief executive of Amber Alert GPS, most customers buy the device for children between the ages of 2 and 10 — children old enough to be mobile, but too young to carry a cellphone. Still, the Amber Alert can act as a quasi-phone; with a press of a button on the device, your children can send a text or initiate a voice call with you, and you can also dial in to the tracker and listen to their surroundings.

I found the Amber Alert extremely simple to set up and use. The company’s Web site, which allows you to configure and monitor the tracker, is well designed and intuitive, and its iPhone and Android apps also work quite well. Amber Alert offers more customizable alert settings than any other child-tracking system I tested: among them, there’s an option to receive an alert each time your child comes within 500 feet of an address listed on a sex-offender database.

The only downside to the Amber Alert is its price. The device sells for $200, and it requires a service plan, which goes for $14.99 a month for basic tracking features, and $24.99 a month if you would like extras, including voice-calling and sex-offender alerts.

Another child-tracking device I tested, the Securus eZoom, is slightly larger than the Amber Alert and doesn’t have some of that device’s advanced features (like voice calling), but it is also significantly cheaper. The eZoom sells for $99.99, and its monthly plan is $19.99. If you pay for two years at once, you can bring the price down to $12.99 a month.

Securus also makes a couple of GPS devices for other uses. The eCare is meant for seniors who need medical help. In addition to tracking, it has an SOS button that initiates a voice call to an emergency call center. The eCare sells for $99.99, with a $29.99-a-month service plan. Finally, there’s Securus’s dog tracker, called SpotLite, a water-resistant, two-ounce module that hooks on your pet’s collar. (The company says the device is best for dogs weighing more than 10 pounds; it’s not recommended for cats because of its size.)

Then there is a GPS device designed for keeping track of your most important possession: yourself. The SPOT Satellite GPS Messenger, which sells for $119.99 and requires a $99-a-year contract, is meant for adventurous types who routinely wander far off the grid.

If you find yourself in an emergency in a place without any cellphone connectivity, you can hit a button on the SPOT to alert rescuers to your location; the device works almost anywhere in the world as long as you have a clear view of the sky. If you’re not in trouble, you can use the SPOT to send a message letting your friends know you’re fine. They can also track your progress across the Outback on a map. The SPOT has led to dozens of rescues, including of two people whose plane crashed into the Gulf of Mexico early in October.

This article has been revised to reflect the following correction:

Correction: October 22, 2012

An earlier version of this article incorrectly stated the name of the chief executive of Securus. His name is Chris Newton, not Newtown.

Home Tech: Tracking Family With GPS (Don’t Forget the Dog)

So the other day, I slipped a GPS tracking device into my wife’s car before she headed off to work. I put another tracker in my 2-year-old’s diaper bag and sent him off to the nanny for the day. I still had a few trackers left, and my parents were in town, so I also threw one into their vehicle while they took my son out to the park.

Of course, I had never suspected any wrongdoing and, later on, when I reviewed the trails left by these GPS devices, they turned up nothing untoward. My spying was meant only as an experiment, but I still felt like a heel.

As well I should have. It’s precisely because of mischief like mine that tracking devices get a bad rap. These small gadgets work by connecting to GPS satellites and cellular networks to follow subjects and report back their locations to their masters. Once I sent them out into the world, I could look up the trackers online, either on the Web or through a smartphone app. They could also be configured to send me alerts based on various criteria. If my wife’s car left her office parking lot during the day or my parents’ vehicle broke the speed limit, I might get a text alert. If your mind reels at the universe of Maury Povichian possibilities contained within these gadgets, you’re not alone.

Yet after chatting with representatives at several GPS tracking companies and trying out their products, I learned that there are many less icky, entirely defensible uses for such devices. For example, some parents use trackers to make sure their children get to school and back safely each day. Others build them into their teenage drivers’ cars so they can be alerted if the kids drive recklessly. There’s also the elder-care market — GPS trackers embedded into medical-alert devices can help locate and provide emergency help for parents with Alzheimer’s.

And don’t forget the dog: a tracker attached to its collar can let you know if it wanders out of your yard, and help you find it if it doesn’t come back. The more I heard about these devices’ applications, the less unseemly they began to feel; indeed, for many people, GPS tracking could soon become a regular part of life.

Among the companies pushing for this future is Amber Alert GPS, a Utah-based firm that was founded in 2007 after Russell Thornton, a businessman, lost his 3-year-old son at an amusement park. After a frantic 45-minute search, Mr. Thornton found the boy hiding in a play structure, but he was traumatized by the incident, and it spurred him to build a device that would help other parents avoid that fate.

Amber Alert’s tracker is about the size of a child’s palm, and it looks a bit like an old-school pager. It can be slipped into a pocket or backpack, or placed in a carrying case attached to a child’s belt loop. According to Carol Colombo, the chief executive of Amber Alert GPS, most customers buy the device for children between the ages of 2 and 10 — children old enough to be mobile, but too young to carry a cellphone. Still, the Amber Alert can act as a quasi-phone; with a press of a button on the device, your children can send a text or initiate a voice call with you, and you can also dial in to the tracker and listen to their surroundings.

I found the Amber Alert extremely simple to set up and use. The company’s Web site, which allows you to configure and monitor the tracker, is well designed and intuitive, and its iPhone and Android apps also work quite well. Amber Alert offers more customizable alert settings than any other child-tracking system I tested: among them, there’s an option to receive an alert each time your child comes within 500 feet of an address listed on a sex-offender database.

The only downside to the Amber Alert is its price. The device sells for $200, and it requires a service plan, which goes for $14.99 a month for basic tracking features, and $24.99 a month if you would like extras, including voice-calling and sex-offender alerts.

Another child-tracking device I tested, the Securus eZoom, is slightly larger than the Amber Alert and doesn’t have some of that device’s advanced features (like voice calling), but it is also significantly cheaper. The eZoom sells for $99.99, and its monthly plan is $19.99. If you pay for two years at once, you can bring the price down to $12.99 a month.

Securus also makes a couple of GPS devices for other uses. The eCare is meant for seniors who need medical help. In addition to tracking, it has an SOS button that initiates a voice call to an emergency call center. The eCare sells for $99.99, with a $29.99-a-month service plan. Finally, there’s Securus’s dog tracker, called SpotLite, a water-resistant, two-ounce module that hooks on your pet’s collar. (The company says the device is best for dogs weighing more than 10 pounds; it’s not recommended for cats because of its size.)

Then there is a GPS device designed for keeping track of your most important possession: yourself. The SPOT Satellite GPS Messenger, which sells for $119.99 and requires a $99-a-year contract, is meant for adventurous types who routinely wander far off the grid.

If you find yourself in an emergency in a place without any cellphone connectivity, you can hit a button on the SPOT to alert rescuers to your location; the device works almost anywhere in the world as long as you have a clear view of the sky. If you’re not in trouble, you can use the SPOT to send a message letting your friends know you’re fine. They can also track your progress across the Outback on a map. The SPOT has led to dozens of rescues, including of two people whose plane crashed into the Gulf of Mexico early in October.

This article has been revised to reflect the following correction:

Correction: October 22, 2012

An earlier version of this article incorrectly stated the name of the chief executive of Securus. His name is Chris Newton, not Newtown.

Privacy Advocates and Advertisers at Odds Over Web Tracking

BERLIN — An effort to develop an easy way for consumers around the world to avoid being tracked and targeted by Internet advertisers appeared to hit an impasse Thursday, as privacy advocates and industry representatives accused each other of scuttling the process.

The closed-door meeting organized by W3C, the global standards group that promotes good governance of the Internet, failed to produce a consensus on how to allow consumers to simply and effectively declare their “do not track” preferences on Web sites. The talks foundered on main issues like the extent and types of data that advertisers could continue to collect even after consumers indicated they no longer wanted to be followed.

The conference, which concludes Friday, is not expected to produce a final resolution, and other meetings could be scheduled before the end of January, when the group is set to disband. But the stakes for Internet users are high and boil down to who determines the limits and protections of online privacy on the Internet: the businesses running the Web, which is largely the current status quo, or the consumers who use it.

For the moment, privacy advocates say the status quo is winning out.

“It seems the process has been hijacked by commercial interests,” said Jacob Kohnstamm, the chairman of the European Commission’s top privacy panel, the Article 29 Working Group. Mr. Kohnstamm’s panel is an observer at the meetings, whose participants included about 40 Internet companies, advertising groups and privacy advocates.

Mr. Kohnstamm, who is also president of the Dutch Data Protection Authority, said proposals before the W3C would let advertisers continue collecting personal data through each mouse click, without obtaining prior consent.

“The Do Not Track standard would be utterly deceptive to users and act as a disguise for continuation of unfair and intransparent business practices,” he said.

If adopted in this fashion, European regulators would then be left to police advertisers’ actions, initiating proceedings based on their own investigations or on individual complaints, he said.

Advertising industry representatives attending the meetings were equally vocal in their displeasure over attempts to ban their ability to follow what people view online, which they argued would undermine the advertising-supported model used by most free services on the Web.

“This basically attacks the financing model of the Internet,” said Dan Jaffe, the executive vice president of the Association of National Advertisers, a New York trade group representing 460 companies that spend $250 billion in advertising each year. “If these various proposals limit this type of advertising, it will cut down on the amount of free information that consumers have on the Internet, create incentives for online companies to erect pay walls, and lead to more shotgun forms of advertising.”

Thomas Roessler, who is leading the meeting in Amsterdam for the W3C, said that several “open issues” remained to be solved, though he declined to specify which ones because the discussions were under way.

But he said the W3C, a group set up by one of the computer engineers who designed the World Wide Web, Timothy Berners-Lee, was optimistic that an effective compromise could be reached.

“I still have some measure of confidence we will come up with a workable solution,” Mr. Roessler said.

The idea of giving consumers a simple and effective way to avoid being tracked by advertisers originated in 2011 at Mozilla, the makers of the Firefox Web browser. Currently, the only way consumers have to opt out of tracking is to visit Web sites sponsored by the ad industry like www.aboutads.info in the United States or www.youronlinechoices.com in Europe to request they no longer be followed. But not all Web sites honor those preferences.

“We are still optimistic we will get to a point where this becomes meaningful to consumers,” said Alex Fowler, the global privacy and policy leader for Mozilla, which is participating in the forum in Amsterdam.

But he acknowledged wide differences among the participants, adding: “It might take more time than people are hoping in the short term.”

This article has been revised to reflect the following correction:

Correction: October 4, 2012

An earlier version of this article incorrectly stated that Facebook did not participate in the W3C talks in Amsterdam. Facebook is participating in the summit.