My thought is enforcing the philosophy that the police first responsibility is to safeguard the lives of the public. Not their own lives, not the lives of their fellow officers, but the lives of the 'civilians' (ie non-police) they are supposed to serve and protect, including "suspects."
I include "suspects," because in this country we are all innocent until proven guilty in court. There are numerous reasons somebody might be shooting at, or otherwise threatening police officers that would not result in them being found guilty of attempted murder in court, so the police should not be empowered to decide guilt and innocence on the side of the road, and execute suspects in so-called self-defense.
Apprehend suspects alive at all cost, including your own life. As a police officer you should have no "right to self-defense." Deadly force can be used to protect civilians from death or serious injury, but it can not be used to protect police. If you cannot put the lives of the public (including suspects) ahead of your own life then get a new job. Stay a 'civilian' and you can keep your right to self-defense.