Principle of Legality in Criminal Law

The government can't just invent a crime to punish you after you've already done something!

That's a huge deal in criminal law, called the "principle of legality." It means for an act

to be a crime, the law must have clearly said so *before* you did it.

No vague rules, no surprise charges. Your conduct has to be unlawful, you gotta be accountable,

and the state proves it. But if there wasn't a clear law against it beforehand,

you can't be convicted. So, the rules have to be set first, always!