It's not a requirement, but about 21% of them do so. No joke. Close to 1/3 suffer from depression too, but that doesn't typically set in until they've started their careers.
No, it means they must know how to make every alcoholic drink. (Drinking them all then being able to crawl OVER the counter.. that's "passing the bar")
A principle in common law is "void for vagueness". The law must be simple enough and published in a place with free access so that an average person can read it and understand it.
The American justice system is so vague that an entire industry exists to try to understand it.
The entire body of laws could be declared "void for vagueness" at any time.