The “void for vagueness” doctrine argues that a law cannot be enforced if it is so vague or confusing that the average person could not figure out what is being prohibited or what the penalties are for breaking that law. Vagueness is generally considered to be a due process issue, because a law that is too vague to understand does not provide adequate notice to people that a certain behavior is required or is unacceptable.
Vagueness is an argument typically used in criminal cases, when a law that is supposed to prohibit a certain behavior is too vague or confusing for people to understand what behavior they’re supposed to avoid, on penalty of being charged with or convicted of a crime. However, laws that cover civil matters are occasionally challenged for vagueness as well.
A law can be unconstitutionally vague in one of two main ways. First, the law may be void for vagueness if it does not adequately explain or state what behavior the law is meant to affect. If the average citizen cannot figure out from reading the law what he should or should not do, a court may find that the law violates due process. Second, a law may be void for vagueness if it does not adequately explain the procedures that law enforcement officers or courts must follow when enforcing the law or handling cases that deal with certain legal issues. Specifically, a law may be found to be unconstitutionally vague if it gives a judge no idea how to approach or handle a case based on that law.
The “overbreadth” doctrine is related to the vagueness doctrine. Under the overbreadth doctrine, a law is unconstitutional or void for being too broad if it covers activities that are protected by the federal Bill of Rights or the rights listed in state constitutions. Unlike vagueness doctrine, arguments that a particular law is overbroad typically do not appear in criminal cases. Instead, most overbreadth arguments come up in First Amendment cases, where a statute tries to prohibit or to make criminal a behavior protected by the First Amendment.
The First Amendment protects five basic rights: the rights to freedom of speech, freedom of the press, freedom of religion (both to have a religious preference and to be free from government mandates that one practice or avoid practicing a certain religion), the freedom to assemble peaceably, and the freedom “to petition the government for redress of grievances.” When a law is unconstitutionally overbroad, it often is because that law prohibits some behavior that is otherwise protected by the First Amendment.
Overbreadth is related to vagueness because an overbroad law is often too vague for a reasonable person to understand what behavior is covered and what behavior is not. In order to avoid breaking an overbroad law, then, many people will voluntarily choose not to engage in behavior protected by the First Amendment or another basic right, just to be sure they’re not accidentally breaking the overbroad law. Since these laws either infringe on basic rights or encourage people to avoid exercising basic rights, most courts recognize that anyone who is affected by an overbroad law has standing to challenge the law’s overbreadth on behalf of all persons affected by that law – an exception to the usual rules of standing and those that cover class actions.