Well, this is a bit of a doozy. This case — via the Institute for Justice — involves a possible First Amendment violation but somehow ends with a judicial blessing of cops who make things up after the fact to justify an arrest that has already taken place.
That’s literally what happened here. Mason Murphy was walking down a Missouri road when he was accosted by Officer Michael Schmitt. From the opening of this very unfortunate decision [PDF]:
Schmitt stopped his car, approached Murphy, and asked Murphy to identify himself. Murphy refused to identify himself, and Schmitt put Murphy in handcuffs after nine minutes of argument. Murphy asked why Schmitt arrested him, and Schmitt refused to answer.
So far, it would appear no criminal act was committed and that the cuffing of Murphy by Schmitt was in retaliation for Murphy’s refusal to identify himself and, First Amendment-wise, his refusal to shut up.
…
So it appears the problem was what Murphy sued over. His lawsuit claimed his first amendment rights were violated because he was exercising free speech and the cop retaliated. I think the key point is that Murphy agreed there was probable cause to arrest him.
He should have claimed a violation of his fourth amendment rights for the unlawful seizure as he was arrested without probable cause. Once he agreed there was probable cause, that negated that argument.
It sucks, but this is why having a good lawyer can help. And if you want to argue that a court should be able to elaborate beyond what was brought in the lawsuit, consider conservatives would have no qualms about shoving abortion restriction and all manner of bullshit through using tangentially related cases.
(This is a more detailed summary of the case if you want to read more)
(Also this little grab bag of all kinds of other fascinating decisions and rulings is well worth reading)