Definition - What does Vagueness Doctrine mean?
The vagueness doctrine is a doctrine that states that criminal laws that make certain actions or behaviors prohibited need to be clear about what is actually being prohibited. In other words, the wording of the law should be easy for a person of average intelligence to be able to understand; it should not be overly extensive or overly complicated, leading to confusion.
Justipedia explains Vagueness Doctrine
The problem with laws that are vague is that they can lead to misinterpretation by both normal citizens and law enforcement. For example, if a law says that it is illegal to park a car on a street on certain days of the week, then this law would not meet the criteria of the vagueness doctrine. The reason is because the law does not inform citizens or law enforcement about exactly which days of the week it would be illegal to park one's car on the street.