Corrupt police officers should get life imprisonment no matter how small the criminal transgression if it is an intentional act of disregarding the law.
I have a few reasons for feeling this way.
Firstly, as a matter of principle.
If you're prepared to lock somebody up (and quite possibly fuck their life up) for breaking the code you work to enforce, then you have no business breaking that code.
When the stakes are this high, hypocrisy is simply inexcusable.
Secondly, this will drastically reduce police corruption.
Thirdly, it will reduce the numbers of police officers, which I support 100%. To combat this, society may come to the conclusion that it must change the laws that are keeping people out of policing, and things like prohibition will take a blow. If not, there'll be less cops to enforce draconian laws like this. It's a win-win situation as far as I'm concerned.
The amount of policing that goes towards violent crime is not that great, and remaining resources will prioritise serious crime anyway, so I don't see there being any bad effects on that level.