Cambridge police lieutenant sues gun maker, city over what he says are guns that fire on their own

Cambridge PD Lt. Thomas Ahern says only a well placed cell phone prevented serious injury when his gun discharged on its own as he sat in a SWAT van during the 2019 MayFair festivities. He's suing gun maker Sig Sauer for selling what he claims is a defective device and his own city for what he says is punishment for objecting to its bulk purchase of the guns over his objections.

In a suit filed this week in US District Court in Boston, Ahern says that Cambridge agreed in 2018 to buy Sig Sauer P320 guns for all its 280 officers even after he raised concerns about its safety, in particular what he alleges is its propensity to fire on its own even without the trigger being pulled. Ahern said he grew so concerned that he raised the issue at every opportunity, even at off-duty barbecues and parties with other officers, including his brother, also a lieutenant on the force.

Ahern says he was in the SWAT van with several other officers on May 19, 2019 - just in case of a terrorist attack at the high-visibility MayFair - when his gun went off while he was inspecting his holster and he was holding the gun.

At no time did Lieutenant Ahern touch the trigger, and no other item touched the trigger. The bullet impacted Lieutenant Ahern’s left thigh over his duty pants, deflected off a magnet affixed to his cellphone in his left pocket, entered an equipment bag on the floor of the van, and came to rest inside a ballistic helmet. ...

The magnet attached to the back of Lieutenant Ahern’s Apple iPhone was the only object that prevented Lieutenant Ahern from incurring severe injury or death

Ahern said that since this incident several other Cambridge officers have had their Sig Sauer guns discharge without them pulling the trigger - and that officers across the country have reported similar incidents.

He alleges that his superiors insisted he falsely agree that he was at fault for the gun going off and that because he wouldn't, he was not allowed to attend training sessions that might help him advance to to becoming a superintendent - and that, in fact, when he applied anyway, was told he would not get the post without first acknowledging his blame.

In his complaint, Ahern is seeking compensatory damages from the gun maker for what he charges is a defective product, and from Cambridge for emotional distress and the loss of income he would have made had he been promoted.

Complete complaint (2.6M PDF).