"This an area where the law clearly hasn't kept up with the times as you think about America today," Wyden said. "All over the country, you've got folks with a cellphone or a handheld electronic device and they basically use it for just about everything in their lives. With everybody out there doing their thing--googling and e-mailing and texting and loving to send a tweet, I don't think they're aware that private companies have this unbelievable area of information about what they're up to."
Llaw enforcement agencies like the Bureau of Alcohol, Tobacco, Firearms and Explosives use the information to track suspects.
"We abide by the laws as they are written," said Donna Sellers, an ATF spokeswoman. She would not comment on the agency's stance on the use of warrants. But, last year, the Justice Department defended warrantless tracking by all federal agencies in Third Circuit Court of Appeals.
Wyden proposes legislation that will create a roadmap for the use of geolocation technology by authorities -- calling the use akin to searching people's homes or reading their mail. He outlined elements he wants to see addressed in a speech at the Cato Institute on Wednesday.
The law should require authorities to get a court-ordered warrant before accessing American's geolocation information, Wyden said. It should apply to both cell phones and less-obvious GPS units -- like those installed by the government in newer cars.
"People are being monitored 24/7 for weeks on end and that's what we really need to get at with some clarity and it ought to apply to all the technologies," he said. "This is a significant intrusion on privacy. We ought to do a better job of securing privacy as we look to the overall well being of the community."
The Center for Democracy and Technology, a nonprofit group the encourages free expression and privacy in communications, supports Wyden's proposal.
"We're excited about this," said Jim Dempsey, the vice president of public policy for CDT. "We've long been in a position this kind of tracking -- either with GPS or with cell phones -- should be treated as a search and seizure, and should be authorized only with the use of warrants."
There's a significant difference, Dempsey said, between tracking people's location and folks freely offering their whereabouts through check-in apps like FourSquare.
"All of the consumer-based services are user-controlled," he said. "The user gets to decide the fact that you disclose some information to the world."
Wyden said he is crafting the legislation with Rep. Jason Chaffetz, R-Utah. Chaffetz was not available to comment on the proposed bill.
Wyden said he plans to introduce the legislation in the "next few weeks."