I don't know. We are at a place where the relationship between the police and the communities they serve is a very unhealthy one. This is the problem that needs to be addressed first. Many professions require continuing education in order to maintain a license. Perhaps police should be required to perform a number of 'community engagement' hours every year to remain employable. For example, this could be serving a soup kitchen, reading to kids at a local library, helping with a community fair or festival, or coaching a local youth team. This isn't a fix, but it could be a start. Rules and 'sensitivity training' are not going to fix the us vs. them mentality that has poisoned the police/community relationship. It's not enough to prevent police from doing harm to a community, you need to create the conditions where they will not be willing to.