In an ambulance speeding through Staten Island, a patient began tending to his own needs. He unbuckled the straps of the gurney on which he lay, and opened the doors of the moving vehicle.

The patient, Yaugeni Kralkin, then jumped out, tumbling onto the asphalt and falling unconscious.

On Friday, Mr. Kralkin, 56, filed suit in State Supreme Court on Staten Island against the city, the Fire Department and the four emergency medical workers who were administering to him that night last June.

Mr. Kralkin has accused the workers of failing in their duties, saying they did not stop him from exiting the ambulance and are thus responsible for the injuries he sustained hitting the pavement on Richmond Avenue.

The seemingly strange assignation of blame hinges on one point: Mr. Kralkin was incredibly drunk, with a blood-alcohol level so high he was unaware of his actions, he says, even as he unbuckled straps and ultimately dived from the vehicle, according to his lawyer. The emergency medical workers failed in their duty to protect him, the lawsuit contends, even from himself, in his inebriated state — attributed to a bottle of cognac.