Ok, so what if the guy you shoot ends up being an undercover cop and the guy in uniform is a bad guy going door to door raping people?
Ok, while maybe not completely outside the realm of possibilities, that is pretty far fetched. Let's remain realistic here.
I'm not saying that there aren't police impersonators, nor am I saying that there are plain clothes officers that will sometimes be involved in an altercation without assistance readily available. However, I would say that the chances of those two things happening simultaneously is so miniscule that it would not create a valid argument.
Despite stories you may hear, there just aren't a lot of bad guys dressing as uniformed police officers (at least here in the U.S.). When you do hear about it they are making the fake traffic stops. When these situations do occur, it is even more unlikely that it is going to be a plain clothes officer responding. Ok, now you say, maybe the plain clothes officer was staking out that neighborhood for said bad guy. Rest assured if he was going after a guy like that there is a swarm of officers with him.
All that aside, if we remain realistic you are going to see a lot of other indicators as well, i.e. marked patrol car, etc. Even if you did not, I would argue that it is pretty easy to figure out who is the aggressor (perp) and who is the good guy (officer) on the face of it.
I'll respect anyone's right to not get involved based on their own moral convictions, but to use a far-fetched possibility for that same action is without merit.
This is what I was thinking. Either way, you might be able to convince the DA that you were trying to do the right thing.
That's right. It's called a good samaritan law. True, not all states have laws that would cover a good samaritan in such a situation. However, you are unlikely to find a police department that would forward such charges to a DA, less likely to find a DA who will prosecute the case, and even less likely to find a jury that would convict.