I don’t think so. Or at most it talks about “reasonable effort” or something vague like that.

/someone who discovered an over-employed person on his team and wondered the same thing

Fascinating. My locality is usually kinda lax but it's something that we have.

I would have thought that with the litigious culture in the US and non-competes etc... this would all be watertight. Seems kinda ridiculous that with a non-compete you can't work for a competitor once you've quit but you're free to do so while you still work for your employer, lol.