BASKING RIDGE, NJ — Be careful what you send to friends via your constant companion, the cell phone. It could rat you out down the road. Like email and instant messages, cellular text messages usually are archived by service providers.Setting an unfortunate precedent, the U.S. Justice Department has gotten a federal judge’s approval to obtain archived cellular text messages without first getting a warrant.

The case revolves around Susan Jackson, a woman who pleaded guilty to wire fraud in the form of transferring funds from her employer’s bank account to her own. During sentencing, the Secret Service asserted letters in support of minimal jail time from friends, family, and employers had been altered, thereby opening Jackson to additional charges of obstruction of justice.

One of Jackson’s alleged supporters told investigators Jackson used text messaging and email to urge him to play along with the alterations, and that was enough to send the DOJ to Verizon’s door with a warrantless subpoena for the company’s archives. The subpoena was issued under a section of the law that allows prosecutors to claim records are “relevant” to an investigation without establishing probable cause for a search. The DOJ claimed the move was proper, because the text messages were “opened communications” — messages already read by the recipient — and therefore no longer necessarily private.

Jackson’s lawyer disagreed, but on October 30th, U.S. District Judge Richard Roberts sided with the prosecution and ordered Verizon to comply.

In addition to providing “LUDs,” or lists of calls sent and received by Jackson’s cell phone, Verizon provided information about the owners of the phone numbers and an accounting of the complete contents of every text message Jackson sent or received between June 6th and October 31st. The company also handed over a transaction log for Jackson’s email account, although it does not archive the contents of email messages so it could not provide that information.

In a concession to attorney-client privilege — which Jackson alleged in the case of some of the messages — the court appointed a magistrate to review the Verizon files before turning all of them over to the prosecution, where they now await further action.

Jackson’s is not the first case in which text messages have played a pivotal role. Text messages made an appearance in the attempted murder of rapper 50 Cent, and the judge in the Kobe Bryant sexual-assault case ruled text messages sent between the victim and her friends in the hours prior to her encounter with the NBA star were “highly relevant” to the case.