Fearsome Forehand would be the main person that I would think could answer a question like this.
I would also say, that I don't think it would be a "crime", as in a crime you could be arrested for.
At most, in the US (because we sue for everything), I could see someone attempting to file a lawsuit for medical bills or something, but I think when you step on a tennis court to play a match, you "assume the risk" that you could be hit by a correctly struck or errantly struck tennis shot.
There would be more of a case if you were on another court, and a player from the adjacent court got mad and negligently fired a smash that hit you or something like that. But in the normal course of the match, my thought would be no.