Government officials must seek a warrant to compel the disclosure of cell phone location data, a federal district court ruled, holding that a federal law allowing the government to obtain some information without a warrant violates the Fourth Amendment.

In a one-page order upholding a magistrate judge’s decision, U.S. District Judge Lynn N. Hughes, of the Southern District of Texas, held Nov. 11 that records showing the “date, time, called number, and location of the telephone when the call was made” are constitutionally protected, and thus the government needs a warrant based on probable cause to compel the disclosure of such data. That standard is higher than the standard required for a court order under the Stored Communications Act, which requires a government entity to demonstrate that there are “specific and articulable facts showing that there are reasonable grounds to believe” the contents of or records about an electronic communication are “relevant and material to an ongoing criminal investigation.”

The Wall Street Journal notes that “more than a dozen magistrate judges have written opinions denying applications for court orders to track cellphones without search warrants” since 2005, and the Supreme Court heard oral arguments earlier this month on whether the Fourth Amendment requires the government to obtain a warrant in order to continuously track individuals using GPS.

The issue has drawn attention in Congress as well. A bill pending in the Senate, sponsored by Judiciary Committee Chairman Patrick Leahy (D-VT), would amend the statute to prohibit the government in most circumstances from obtaining geolocation information unless the government obtains a warrant or an order from the Foreign Intelligence Surveillance Court. The bill also would require a warrant to compel the disclosure of the contents of a stored electronic communication. But the bill still would allow the government to obtain other information about subscribers or customers, including telephone connection records, with a court order, or in some cases a subpoena.