Suppose Bob is a news reporter who honestly reports bad things about the police chief. The police chief doesn't like it, and he wants to arrest Bob for it, but he knows he can't legally do so because Bob has protected speech. Instead, the police chief decides to find an alternative reason to arrest Bob. He digs through Bob's entire life looking for any one speck of dirt, and when he finds one, he arrests him for that (even, or especially, in a case when the dirt is so minor that Bob would not have been arrested for it otherwise). Or, if he finds no dirt at all, he just invents an accusation from thin air and arrests him for that, forcing Bob to "prove his innocence" — which is a punishment in itself.
Is there a quick name for this phenomenon? When I bring the idea up in conversation, I'm tired of calling it "They don't arrest you for X in this country, but there are so many things that have been outlawed that they can just invent a reason to arrest you for anything else, effectively subverting your right to X." I'm looking for something easy to say like "Side Arrest" or "Alternatively-Motivated Arrest" or something. If there isn't a term for it, I plan to invent one, but I want to make sure there isn't already something else in use.