When can I sue for false imprisonment?
You can try to sue, but most likely you won’t win. Security at football games (and other venues) have the right to hold someone if they feel a crime has been committed (in this case, throwing the beer) while they conduct their investigation and/or until the police come (which may take a couple of hours depending on the size of the city). While it may seem unfair because you say you didn’t throw the beer, “false imprisonment” doesn’t really apply in this case. You could however try to file a complaint or sue or both because of the treatment you received. But if you were drinking, it would still be a tricky thing to win. They could claim you were hostile or beligerent hence their treatment of you.
First you can sue for anything. Second you must however have reason for the damages and have filed a claim that has been denied. Third private security can hold you for a reasonable time before turning you over to the polce (up to six hours is reasonable). Dont delay on your claim, most states have a very small window from denial of claim to filing of lawsuit and be prepared to front at least 2500 for a good nuisannce lawyer.