of the United States
In American constitutional law, a statute is void for vagueness and unenforceable if it is too vague for the average citizen to understand. This is because constitutionally permissible activity may not be chilled because of a statute's vagueness (either because the statute is a penal statute with criminal or quasi-criminal civil penalties, or because the interest invaded by the vague law is sufficiently fundamental to subject the statute to strict scrutiny by a court determining its constitutionality). There are several reasons a statute may be considered vague; in general, a statute might be void for vagueness when an average citizen cannot generally determine what persons are regulated, what conduct is prohibited, or what punishment may be imposed. For example, criminal laws which do not state explicitly and definitely what conduct is punishable are void for vagueness. A statute is also void for vagueness if a legislature's delegation of authority to judges or administrators is so extensive that it could lead to arbitrary prosecutions. A law can also be "void for vagueness" if it imposes on First Amendment freedom of speech, assembly, or religion.
The "void for vagueness" doctrine does not apply to private law (that is, laws that govern rights and obligations as between private parties), only to laws that govern rights and obligations vis-a-vis the government. The doctrine also requires that to qualify as constitutional, a law must:
The concept of vagueness in law, particularly in the context of the void-for-vagueness doctrine, has ancient roots. It is believed to originate from the Roman law maxim, "Nulla crimen sine lege" (no crime without law). This principle was echoed by English jurist Sir Edward Coke, who emphasized the importance of laws, especially penal laws, being "plainly and perspicuously penned." This sentiment was further developed by Sir William Blackstone in his "Commentaries on the English Constitution," where he highlighted the necessity for laws to clearly define the rights to be observed and the wrongs to be avoided. Montesquieu, in his work "Spirit of the Laws," advocated for laws to be concise, simple, and free from vague expressions. These early thoughts undeniably influenced American legal commentators and jurists.
The void for vagueness doctrine derives from the Due Process Clauses of the Fifth and Fourteenth Amendments to the United States Constitution. That is, vague laws unconstitutionally deprive people of their rights without due process.
The following pronouncement of the void for vagueness doctrine was made by Justice Sutherland in Connally v. General Construction Co., 269 U.S. 385, 391 (1926):
[T]he terms of a penal statute [...] must be sufficiently explicit to inform those who are subject to it what conduct on their part will render them liable to its penalties… and a statute which either forbids or requires the doing of an act in terms so vague that men of common intelligence must necessarily guess at its meaning and differ as to its application violates the first essential of due process of law.
The void for vagueness doctrine requires that laws are so written that they explicitly and definitely state what conduct is punishable. The doctrine thus serves two purposes. First, all persons receive a fair notice of what is punishable and what is not. Second, it helps prevent arbitrary enforcement of the laws and arbitrary prosecutions. The void for vagueness doctrine developed because, "When Congress does not set minimum guidelines to govern law enforcement, there is no limit to the conduct that can be criminalized.": 1303
There are at least two ways a law might be attacked for being unconstitutionally vague:
Both scienter and objective criteria that specify the harm to be protected against are necessary to limit vagueness in criminal statutes (Compare page 9 of ). To satisfy the Due Process Clause of the Fifth Amendment, individuals are entitled to understand the scope and nature of statutes which might subject them to criminal penalties. Thus, in Skilling v. United States (2010), it was held that a "penal statute must define the criminal offense (1) with sufficient definiteness that ordinary people can understand what conduct is prohibited and (2) in a manner that does not encourage arbitrary and discriminatory enforcement."
Unconstitutional vagueness is a concept that is used to strike down certain laws and judicial actions in United States federal courts. It is derived from the due process doctrine found in the Fifth and Fourteenth Amendments to the United States Constitution. The doctrine prohibits criminal prosecution for laws where it is impossible to reasonably understand what conduct is prohibited.