Okay kiddo, let me explain the principle of legality in French criminal law in a way that's easy for you to understand.
The principle of legality means that nobody can be punished for something that is not specifically forbidden by the law. This means that before someone can be convicted of a crime, there must be a law in place that clearly states that the action they took is illegal.
For example, if there is no law that says it is illegal to ride a purple bicycle on Thursdays, then someone cannot be punished for doing so. This is because they did not break any specific law.
The principle of legality is important because it helps to protect people from being punished unfairly or arbitrarily. It ensures that everyone knows what is legal and what is not, and prevents the government from making up rules as they go along.
Overall, the principle of legality is a fundamental part of the French legal system and is essential to ensuring that justice is served fairly and consistently for all.