A use-of-force instructor at the Minneapolis Police Department (MPD) testified Tuesday that officers have never been trained to use the type of knee-on-neck restraint that Derek Chauvin employed against George Floyd.

Driving the news: Johnny Mercil, a lieutenant who has worked in patrol and on the community response team, said that officers are trained to use the "least amount of force necessary" to subdue a suspect, and that a knee on the neck would not be authorized against a suspect who is "under control and handcuffed."

Why it matters: The testimony challenges the defense's argument that Chauvin's actions were necessary in order to subdue George Floyd, and comes one day after MPD chief Medaria Arradondo testified that Chauvin "absolutely" violated department policy when he kneeled on Floyd's neck for over nine minutes.

What he's saying: Mercil testified that active or "assaultive" aggression by a suspect may require up to and including deadly force for "life-saving purposes," but that as levels of resistance decrease — especially once a subject is in handcuffs — officers "should deescalate use of force."

• When shown a photo of Chauvin with his knee on Floyd's neck, Mercil said the position is not and has never been an MPD-trained neck restraint. "We don't train" officers to use legs in neck restraint, Mercil testified, adding that this kind of restraint should involve the inner thigh, not the knee.
• Mercil explained that a neck restraint would not be authorized for a subject who is under control and handcuffed, especially since the neck, head and sternum are more prone to injury than other parts of the body. "It’s very important to be careful" with people, he noted.

The big picture: Previous testimony and footage showed that Chauvin continued to kneel on Floyd's neck even after he was handcuffed and said "I can't breathe" over 20 times.

• Though law enforcement officers have testified that handcuffing people or using force is fairly common for patrol officers, all of those who have appeared at the trial so far have emphasized the importance of using "reasonable" force.
• Mercil said Chauvin received training on proportional use of force as recently as 2018. Minnesota banned chokehold and neck restraints after Floyd's death.

Go deeper:

• Top homicide lieutenant: Chauvin's use of force was "totally unnecessary"
• George Floyd's girlfriend recounts how they met, struggled with opioids
• Witness breaks down after George Floyd video: "I understand him"
• 911 dispatcher testimony at Chauvin trial: "Something was not right"