NEW YORK -- A federal district judge ruled on Wednesday that the government obtained a warrant to locate a suspected tax fraud properly, despite omitting details about the secret cell phone tracking technology it planed to use.

At issue is a device called a stingray that tricks cell phones around it into transmitting their location by spoofing a cell tower. The government got a court order to use a stingray to track down Daniel David Rigmaiden, who is accused of submitting fraudulent tax returns in order to collect millions of dollars worth of rebates.

The government didn't mention, however, that it would need to pretend its stingray was a Verizon Wireless tower to find Rigmaiden, or that it would collect the location of hundreds of innocent third parties' phones in the process. Nevertheless, U.S. District Judge David Campbell denied Rigmaiden's motion to suppress the crucial evidence collected as a result of that search.

In court filings the government had argued, and the court accepted, that the means are not as important as the ends when it comes to warrants. In a separate case, the FBI is fighting a lawsuit over a public records request into stingrays.

"The Court agrees that the Tracking Warrant is not a model of clarity," Campbell wrote. It "did not describe the precise means by which the mobile tracking device would operate, what signals it would send to the aircard, what signals it would capture, or the fact that it would cause some of Defendant’s electricity to be consumed in the process."

Still, he said, citing Supreme Court precedent, "There is no legal requirement that a search warrant specify the precise manner in which the search is to be executed."

Campbell's ruling takes away one of the most promising legal avenues for Rigmaiden to beat the charges against him. But the stakes in the case go far beyond his alleged tax fraud, said Linda Lye, a staff attorney at the American Civil Liberties Union of Northern California, which filed a friend of the court brief on behalf of Rigmaiden.

Although the ACLU believes the FBI and other law enforcement agencies employ stingrays regularly, the federal government is secretive about their use. It's only because Rigmaiden, a dogged jailhouse lawyer who represents himself, filed a bevy of court motions that he was able to uncover the use of the device against him.

"They're using them, there are just very few cases where the government has admitted it," Lye said, adding she is "somewhat dismayed" by Campbell's "very, very disappointing decision."

She believes the government violated Rigmaiden's Fourth Amendment protections against unreasonable search and seizure, and also the rights of his neighbors who were caught up by the stingray. The judge accepted the government's argument that those collateral searches weren't important because the FBI deleted the information collected from them.

But Lye objected, "The Fourth amendment does not have a 'no harm, no foul' rule."

Although the district court's ruling will not be binding on other judges around the country, because the use of stingrays is so rarely litigated, Rigmaiden's case could serve as an important legal reference. The judge, Lye argued, should have treated the government's lack of forthrightness as more than a detail.

"Whenever it gets to the Fourth Amendment and new technology it's a little bit of a game of Whac-A-Mole," she said. "The larger principle here is when the government is using new technology ... it definitely needs to err on the side of providing more, not less information to the courts."