I don't think that Derek Chauvin, nor his fellow officers thought he was doing anything wrong that day. To them, it probably seemed like he was employing an unorthodox pain compliance method on a moderately uncooperative suspect. Had the policy been to immediately suspend "holds," and related acts when a suspect said they were having trouble breathing, Mr. Floyd would probably be alive and Mr. Chauvin, et. al would probably still be working cops. Cops, like most workers, like to improvise on the job. They need to know there are limits so that they do not kill petty thieves.