Lt. Johnny Mercil, the second witness of the day, is a veteran of the Minneapolis Police Department, a practitioner of Brazilian jiu-jitsu and a use-of-force instructor who has trained hundreds of police officers.
His testimony focused on a crucial argument for the prosecution: that Derek Chauvin’s actions last May were not consistent with how officers have been taught to restrain people who are resisting arrest.
Steve Schleicher, a prosecutor, displayed a picture of Mr. Chauvin pinning George Floyd to the ground and asked, “Is this an M.P.D.-trained neck restraint?”
“No, sir,” Lieutenant Mercil responded.
The lieutenant, who is currently on medical leave from the Minneapolis Police Department, is the seventh member of the department to testify for the prosecution in Mr. Chauvin’s trial.
But Eric J. Nelson, a lawyer for Mr. Chauvin, countered with a line of questioning emphasizing the unpredictability of people who are being taken into custody, the possibility that they could stop resisting arrest and then suddenly become violent, and the challenge for police officers in assessing a situation as circumstances shift.
He suggested that Mr. Chauvin’s knee was not the cause of Mr. Floyd’s unconsciousness, and asked Lieutenant Mercil whether a restraint requires pressure on both sides of the neck for the person to go unconscious. “That is what we teach, yes,” he said.
Mr. Nelson repeatedly invoked the chaotic scene around Mr. Chauvin last May, asking Lieutenant Mercil whether bystanders yelling insults at an officer would “reasonably tend to rise alarm in an officer.” He agreed that they would.
Mr. Schleicher, the prosecutor, then asked: “And if they’re saying, ‘Get off him, you’re killing him,’ should the officer also take that into account and consider whether their actions need to be reassessed?”
“Potentially, sir, yes,” Lieutenant Mercil said.