Law enforcement officers who seized cellphones in a hunt for evidence of lewd activity following a wild party at a New Jersey bar last summer have been hit with a federal civil rights lawsuit charging the officers with privacy violations.

Police officers may not search suspects’ cellphones without a warrant, the supreme court ruled 9-0 last year, finding that phones these days “hold for many Americans ‘the privacies of life’” described by Justice Louis Brandeis as protected under the fourth amendment.

What’s unusual about the New Jersey bar case is that the plaintiffs are not the familiar type in these cases: motorists or stop-and-frisk victims outraged by what they say are invasive searches and a willful disregard by police for privacy rights.

The plaintiffs in this case are law enforcement officers themselves, suing through a police union. It’s a case of police charging police with illegal policing.

The trouble began in August 2014 at Texas Arizona Bar and Grill in Hoboken, New Jersey, one day after a graduation ceremony for officer trainees with the Port Authority of New York and New Jersey. The Port Authority polices the bridges, tunnels and ports around New York City and the World Trade Center site.

The trainees hit Texas Arizona to celebrate, but at some point things got out of hand, according to vivid news reports from the time, which the lawsuit calls “pejorative”. The rowdy rookies were said to have harassed a woman, fought patrons and each other, poured themselves drinks and, when they were told to settle down, flashed their new badges and told people to “fuck off”. A bartender called police.

The ensuing investigation by the Port Authority lasted more than a month and involved more than 100 interviews of police officers, customers and staff of the bar, local police officials and others. Nine rookie officers were fired and three were suspended.

The lawsuit alleges that Port Authority investigators abused their authority by coercing the officers under investigation to turn over their personal cellphones so that they could be searched. The lawsuit documents seven separate instances in which rookie officers fearing for their jobs were pressured to unlock their phones for investigators or otherwise to give them access to cellphone content, including from group chat application GroupMe.

The lawsuit, which was brought by the Port Authority Police Benevolent Association and one of the fired officers, seeks compensatory damages and an injunction against future such searches.

“The Port Authority’s policy of searching the cellphones of its probationary employees is an impermissible violation of this fundamental right” to privacy, the suit asserts.

“Over and over again, in interview after interview, Port Authority investigators isolated probationary officers and demanded to review their cellphones. Intimidated by the inquisitorial nature of the investigation, deprived of representation, and fearful they would lose their jobs, the officers complied with the Port Authority directive and relinquished their cell phones to invasive searches.”

The Port Authority “strongly disputes” the charges, it said in a statement. “The conduct displayed by these individuals was appalling, deeply troubling, and did not meet the high standards that all of our sworn police officers vow to uphold,” the statement said.