NEW YORK (CBSNewYork) — How much should the NYPD have to reveal about surveillance technology that can track your cellphone without knowing it.

As WCBS 880’s Alex Silverman reported, police and the New York Civil Liberties Union have a difference of opinion on the subject.

The question went before a Manhattan judge on Tuesday.

Stingrays are devices that mimic cell towers to intercept data and let law enforcement track the phone of somebody for whom they are looking.

In 90 minutes of very technical testimony Tuesday, one NYPD detective revealed he has used Stingrays about 1,000 times.

The specific issue is whether police need to reveal the names and prices of the models they bought. Detective Michael Warner testified that if such information is revealed, it could tip off criminals to police weaknesses and help them avoid getting swept up in the Stingrays’ net.

But Bobby Hodgson of the NYCLU called it a knee jerk toward secrecy.

“This case is also going to decide whether such vague assertions can be used to sort of blanket entire categories of equipment in secrecy,” Hodgson said.

There was no ruling right away Tuesday. Last month, a judge in Brooklyn revealed that police need a warrant to use a Stingray in most cases.