Say a cop out of sheer paranoia (maybe because of your looks) thought you were doing something when you weren't and pulled a gun on you, AND you were armed for self-defense, would you just accept him shooting and likely killing you or retaliate? Generally when it comes to these cops shoot innocent situations, the innocent is never armed with a gun of his own or at all.
But if you shoot a cop in self-defense, you'll get the death penalty or life imprisonment anyway with the law working against you so, with that said, would you rather just die from the cop?