Police unions’ efforts to revoke a regulation requiring Breathalyzer tests for all New York cops who open fire on suspects were shot down in a courtroom yesterday.

Manhattan federal Judge George Daniels rejected three unions’ argument that the rule, which was implemented after four cops shot an unarmed Sean Bell dead in 2006, was unconstitutional.

“Armed police officers are given awesome power,” Daniels wrote in his decision. “The NYPD has a substantial interest in ensuring that its officers — especially its armed officers — are fit for duty.”