A New York state judge has concluded that a powerful police surveillance tool known as a stingray, a device that spoofs legitimate mobile phone towers, performs a "search" and therefore requires a warrant under most circumstances.

As a New York State Supreme Court judge in Brooklyn ruled earlier this month in an attempted murder case, New York Police Department officers should have sought a standard, probable cause-driven warrant before using the invasive device.

The Empire State court joins others nationwide in reaching this conclusion. In September, the District of Columbia Court of Appeals also found that stingrays normally require a warrant, as did a federal judge in Oakland, California, back in August.

According to The New York Times, which first reported the case on Wednesday, People v. Gordon is believed to be the first stingray-related case connected to the country’s largest city police force.

"By its very nature, then, the use of a cell site simulator intrudes upon an individual's reasonable expectation of privacy, acting as an instrument of eavesdropping and requires a separate warrant supported by probable cause rather than a mereorder such as the one obtained in this case by theJustice Martin Murphy wrote in the November 3 decision

A "pen register" warrant, sometimes known as a "pen/trap order," which typically only provides a call log for a particular number, has been used in the era of stingrays to also include location information. Historically, law enforcement officers nationwide have not been forthright with judges when explaining what the devices do.

As Ars has long reported, stingrays can be used to determine a mobile phone's location by spoofing a cell tower. In some cases, stingrays can also intercept calls and text messages. Once deployed, the devices intercept data from a target phone along with information from other phones within the vicinity. At times, police have falsely claimed the use of a confidential informant when they have actually deployed these particularly sweeping and intrusive surveillance tools.

In this case, the suspect, Shuquan Gordon, was located in a Brooklyn apartment building seemingly out of nowhere. This was "an address not previously identified as of any interest to this investigation," as the judge noted.

Brian Owsley, a law professor at the University of North Texas and a former federal magistrate judge, whose 2014 law review article on stingrays was cited numerous times by the Brooklyn judge, told Ars that this ruling fell in line with what he called "positive momentum" toward proper regulation.

"There is still a long way to go," he e-mailed. "Moreover, as good as this decision is, the current progress is more aptly described as two steps forward followed by one step back."