Seeking to regulate the use of cell phone records in investigations by law enforcement, Texas lawmakers are considering a bill that would force police and prosecutors to get a warrant before obtaining such records.

Last month, state Rep. Bryan Hughes, R-Mineola, filed House Bill 1608, which would require law enforcement agencies throughout the state to obtain warrants and prove to a judge there is a probable cause of illegal activity before obtaining cell phone records in their investigations. It would also lift the seals on court orders for the data after 180 days. A companion bill has been filed in the Senate by Juan "Chuy" Hinojosa, D-McAllen, and others have signed on.

Privacy advocates like the American Civil Liberties Union say the bill is necessary because cell phone companies are now able to determine and transmit customers’ specific locations. But some police and prosecutors say that the higher standard of proof would make it harder to catch criminals in certain long-term investigations.

In response to a congressional request last year, wireless carriers reported that they get thousands of requests a day from law enforcement agencies for cell phone information, including text messages and caller locations. Privacy advocates in Texas say they were startled at how common the practice had become

“Right now we’re just guessing on the numbers,” said Matt Simpson, a policy strategist with the Texas branch of the ACLU, “but they seem very high.”

Current technology has eroded “traditional conceptions of privacy,” said Scott Henson, the writer of the criminal justice blog Grits for Breakfast, who shopped the bill around to lawmakers. “This bill ensures that government can’t track your daily movements without a good reason.”

In certain situations, Simpson said, police might track an individual simply for going to an Islamic mosque. That would be a violation of the right to freedom of worship, he said, but under current laws no judge would need to consider the issue before the cell phone records were obtained.

The proposal comes in the wake of a broader federal debate over the use of GPS tracking by law enforcement. In January 2012, the U.S. Supreme Court decided, in the case United States v. Jones, that sticking a GPS device on the care of a suspected drug dealer in the District of Columbia named Antoine Jones constituted a “search."

After the decision, federal prosecutors and Jones’ defense attorneys prepared to go back to trial. A U.S. attorney obtained Jones’ cell phone records, which showed dates and times of calls and the cell towers used, though not Jones’ exact locations, and Jones’ attorneys are asking the U.S. district court in Washington, D.C., to not allow the data at the trial. That issue, as well, could reach the U.S. Supreme Court.

“It may be years before the U.S. Supreme Court catches up with today’s technology,” Henson said. “In the meantime, state law should create a clear and protective privacy standard for Texans.” In June 2011, U.S. Sen. Ron Wyden, D-Ore., and Rep. Jason Chaffetz, R-Utah, proposed a bill with similar requirements to the current Texas proposal in federal cases.

Steve Baldassano, a Harris County prosecutor, said that although the policy change would only affect “historical” investigations — police already need to establish probable cause in “real-time” situations involving kidnappings and chases — it could make it harder to catch certain criminals. Baldassano said that cell phone data might be the only evidence supporting or disproving an alibi at an early stage of an investigation. With this new barrier, he said, “you’d just have to let it go.”

Donald Baker, a commander with the Austin Police Department, took issue with Hughes’ requirement that the court seal be lifted after 180 days, because many investigations last longer than that. “You don’t want that information out there,” he said.

Henson said prosecutors and police could still keep records sealed under public information laws, which allow for information to be kept from public disclosure if "release of the information would interfere with the detection, investigation or prosecution of crime."