What Is Mike Smith Actually Accused Of?

Something happened on December 30, 2017.

Did Mike Smith commit a "sexual assault"? What exactly is that? Is that a form of violence? Did he sleep with a lady? I am researching it, and legally, it says sexual assault can even be unwanted kissing or groping. Being charged with sexual assault is an accusation, not a conviction. Beyond that, he pled not guilty. Did he bang someone who didn't want to be banged? That's not exactly easy to pull off... I have heard of that before, though, if someone was drunk or on drugs, or if they got beat so bad they blacked out. But they would have to prove beyond reasonable doubt that Mike did that, right?