[duado]

Crimes much more serious than tax evasion have grey areas specifically to create room for judicial discretion. Words like “with malice aforethought” or “forcibly” are used in statutes because the law can’t preconceive of every possible way to commit a murder or rape.

[RHSeeger]

And crimes much less serious, too. There's a LOT of US laws that are intentionally vague and/or grant far too much leeway for the justice system. The grants extraordinary power because of edge cases they want the law to be able to handle ("think of the children"). Yet time and time again, it's the average Joe that has the law abused against him. These overly vague laws are used incorrectly, and yet we keep creating them because we don't learn that the people in power cannot be trusted; most of them are good, but it only takes one bad apple to ruin the lives of many people.