Qualified immunity
A term that's often misunderstood because stupid people can't tell the difference between "qualified" and "absolute".

In the United States, qualified immunity is a legal principle that grants government officials performing discretionary functions immunity from civil suits (< two very important words right there) unless the plaintiff shows that the official violated "clearly established statutory or constitutional rights of which a reasonable person would have known".

So you can't sue that cop as a way to get back at him because he pulled you over for going 75 mph in a 55 zone. Or because he arrested you for drinking and driving even though you didn't wanna be arrested.

Qualified immunity does NOT prevent police officers from being charged with crimes (get this through your thick skull), nor does it prevent people from suing the departments the police officers work for.
Idiot: "Hey, did you hear about that cop who shot an innocent man 200 times? I heard he got away with the murder because of qualified immunity."

Guy with common sense: "That's not how qualified immunity works... at all."

Idiot: "But... some guy on Twitter said it, so it must be true!"