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."
This article originally appeared in The New York Times.