The NYPD has to let the public know about the possible health risks of its unmarked X-ray search vans, but not any details of how much it's spending on them or how it has used them, state appeals court judges ruled yesterday.

The investigative news website Pro Publica has been fighting the city in court for four years to get the police department to release documents detailing its use of the X-ray vans, which are supposed to be for counterterrorism cops to detect explosives. Officers can drive the vans alongside cars and buildings and, by spraying them with backscatter X-rays like the kind used in now-discontinued airport scanners, see what is inside. The NYPD has refused to release any information about the devices, other than to acknowledge their existence, and say that they're not used to scan people for weapons. Pro Publica asked for the times and locations of past uses and the cost of the vans, as well as information on how much radiation they're set to emit.

In 2015, a New York Supreme Court judge called the NYPD's argument that releasing details could help terrorists "mere speculation" and "patently insufficient" to justify barring a public accounting. The appeals judges overturned this ruling, writing that, "These materials are exempt from disclosure under FOIL’s law enforcement and public safety exemptions," and agreeing with the NYPD that releasing the logistics information would "hamper NYPD’s counterterrorism operations and increase the likelihood of another terrorist attack."

On the topic of the X-rays that expose anybody in range of a given device to radiation, the judges ruled that the police department failed to justify why releasing information about the radiation dose would help terrorists, and pointed out that information on the health risks of the technology are already widely available.

The appeals judges also rescinded an award of attorney fees to Pro Publica's lawyers. The city Law Department was jazzed.

"We are pleased the court agreed that the police department acted appropriately in withholding information that, if disclosed, would compromise public safety and counterterrorism efforts," spokespeople wrote in a statement.

Pro Publica's president Richard Tofel said he was "disappointed" about what will continue to be secret, but "gratified" about the health information being forced out into the open.

At least 50 U.S. law enforcement agencies have radar devices that allow them to look inside homes and see whether anyone is inside, according to a USA Today report from last year. In 2001, the Supreme Court ruled, in a case involving police use of thermal imaging technology, that any government use of a device not available to the public to "explore details of a private home that would previously have been unknowable without physical intrusion" is unconstitutional without a warrant. In a 2014 decision, federal appeals judges in Colorado declined to rule specifically on the use of a radar device to find a fugitive, but wrote that, "the government’s warrantless use of such a powerful tool to search inside homes poses grave Fourth Amendment questions."