Two bills introduced Thursday in the House and Senate would compel law enforcement agents to obtain a warrant before affixing a GPS tracker to a vehicle, using a cell site simulator to locate someone through their mobile device or obtaining geolocation data from third-party service providers.

The comprehensive bills would also prohibit private investigators and other private individuals from using a GPS device to surreptitiously track someone's location without their consent, thus closing a number of holes that were left open in the wake of the Supreme Court's landmark decision about GPS trackers last year.

The Geolocational Privacy and Surveillance Act (H.R. 1312), introduced in the House by Rep. Jason Chaffetz (R-Utah) and in the Senate by lawmakers Ron Wyden (D-Oregon) and Mark Kirk (R-Illinois), has gained wide support from the American Civil Liberties Union and the Electronic Frontier Foundation, who say the bills are very strong and, if passed, would finally bring legislation up to date with the invasive use of new technologies.

"Police routinely get people's location information with little judicial oversight because Congress has never defined the appropriate checks and balances," said Chris Calabrese, legislative counsel in the ACLU's Washington Legislative Office in a statement. "Under the GPS Act, all that would change. Police would need to convince a judge that a person is likely engaging in criminal activity before accessing and monitoring someone's location data. Innocent people shouldn't have to sacrifice their privacy in order to have a cellphone."

The bills contain some exceptions for national security cases and emergency circumstances, and would also allow parents to use tracking with children.

The bills are aimed at closing loopholes left last year by a Supreme Court decision in U.S. v. Jones, which ruled that attaching a GPS device to a vehicle constituted a search under the Fourth Amendment. The decision stopped short of requiring agents to obtain a warrant for GPS devices, however, and also bypassed the issue of whether warrants should be required to obtain geolocation information collected by service providers from smartphones and car-tracking systems like OnStar.

“Although Jones was a step in the right direction, the Department of Justice is still arguing in court that they do not need a warrant to track someone’s movements using GPS devices or technology. This highlights the need for Congress to step in and provide clear and reasonable guidelines,” said Chaffetz.

Chaffetz is referring to arguments the Obama administration made this week to a federal appeals court in another case that law enforcement agents should not have to obtain a probable-cause warrant to use a GPS tracker. The administration argued that current broad exemptions that allow agents to conduct warrantless searches at borders and in other circumstances should apply to the use of GPS devices as well.

If passed, the new laws would resolve the warrant question for GPS trackers by law enforcement once and for all and would also curb the unfettered use of commercial trackers by private individuals.

The use of GPS trackers for commercial purposes has widened in recent years as more devices have become available. Companies have increasingly been marketing them to parents for use in tracking young children out of safety concerns. But the devices can easily be used to spy on someone other than a minor child in order to track their movements surreptitiously, such as by private investigators or a suspicious spouse.

A North Carolina man was accused of murdering his estranged wife's male friend in 2010 after following her to the man's house with a GPS tracker he purchased at Best Buy.

Under the bills introduced this week, using a GPS tracker for private purposes would be outlawed for private investigators and others in the same way that wiretapping is outlawed.

In addition to the GPS trackers, and geolocation data obtained from service providers, the bills would address another controversial technology being used by law enforcement – cell site simulators, also known generically as stingrays. Cell site simulators spoof a legitimate cellphone tower in order to trick nearby cellphones and other wireless communication devices into connecting to the fake tower, as they would to a real cellphone tower.

When devices connect, stingrays can see and record their unique ID numbers and traffic data, as well as information that points to a device’s location. To prevent detection by suspects, the stingray sends the data to a real tower so that traffic continues to flow.

By gathering the wireless device’s signal strength from various locations, authorities can pinpoint where the device is being used with much more precision than they can get through data obtained from the mobile network provider’s fixed tower location.

Chaffetz introduced a nearly identical bill to the GPS Act in the previous congressional session. That bill got referred to the Judiciary Committee and the Select Committee on Intelligence, but failed to gain the support it needed to progress.

This year, the bill is cosponsored by a bipartisan group of 13 lawmakers, among them former Judiciary Chairman Rep. Jim Sensenbrenner (R-Wisconsin) and current Judiciary Ranking Member, Rep. Jon Conyers (D-Michigan).