In American constitutional law, a statute is void for vagueness and unenforceable if it is too vague for the average citizen to understand. There are several ways, senses or reasons a statute might be considered vague. In general, a statute might be called void for vagueness reasons when an average citizen cannot generally determine what persons are regulated, what conduct is prohibited, or what punishment may be imposed. Criminal laws which didn't state explicitly and definitely what conduct is punishable for example are void for vagueness. A statute is also void for vagueness if a legislature's delegation of authority to judges and/or administrators is so extensive that it would lead to arbitrary prosecutions. Related to the "Void for vagueness" concept is the "Unconstitutional vagueness" concept (see below).
Roots and purpose 
In the case of vagueness, a statute might be considered void on constitutional grounds. Specifically, roots of the vagueness doctrine extend into the two due process clauses, in the Fifth and Fourteenth Amendments to the United States Constitution. The courts have generally determined that vague laws deprive citizens of their rights without fair process, thus violating due process.
[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 is a constitutional rule. This rule requires that criminal laws are so written that they explicitly and definitely state what conduct is punishable. The void for vagueness doctrine thus serves two purposes. First: All persons receive a fair notice of what is punishable and what is not. Second: The vagueness doctrine helps prevent arbitrary enforcement of the laws and arbitrary prosecutions. There is hoewever no limit to the conduct that can be criminalized, when the legislature does not set minimum guidelines to govern law enforcement. (See p. 13 of).
Specific application 
There are at least two ways a law might be attacked for being unconstitutionally vague:
- When a law does not specifically enumerate the practices that are either required or prohibited. In this case, the ordinary citizen does not know what the law requires. Also see Coates v. Cincinnati.
- When a law does not specifically detail the procedure followed by officers or judges of the law. As a guard, a law must particularly detail what officers are to do, providing both for what they must do and what they must not do. Judges must, under the doctrine, have a clear understanding of how they are to approach and handle a case.
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, “[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.”
Theoretical basis 
A number of arguments are presented in favor of the void for vagueness doctrine. The most basic is as expressed by Justice Sutherland: that an individual should not face punishment for violating the law, unless the nature of the prohibited conduct can be understood by a reasonable person. This concept is not unlimited, given that personal ignorance of the law is not generally considered to be a defense, under the doctrine of ignorantia juris non excusat. Nevertheless, the void for vagueness doctrine is seen as protecting an individual's right to due process, including the ability to investigate what is prohibited in a specific situation, and then to live free from fear or the chilling effect of unpredictable prosecution.
A second argument is conceived not as a personal protection, but as a limitation on the state and its ability to initiate criminal prosecutions. If penal statutes are overly vague, it is argued that the state's discretion to prosecute becomes too broad, and potentially subject to abuse through selective enforcement.
One criticism of the doctrine is that there is an inherent indeterminacy in every law, so attempting to eliminate them is folly and only leads to more problems. Another criticism might be that vague laws are actually good, that they allow the judge or jury to apply a single law in a number of situations unanticipated by the legislature.
These might be answered by responding, on the first hand, that the doctrine does not attempt to eliminate ambiguity altogether, but only so far that an average man, in an average situation, might understand the meaning. To the second criticism it might be responded that, indeed, laws should not be impossibly narrow, but in a system that presumes both liberty and innocence, such broad laws as those suggested by that criticism would be undesirable as they would catch in their net many innocent citizens.
Other vagueness tools 
Vagueness does not always lead to a determination of invalidity. Oftentimes, judges will utilize tools[clarification needed] which will help them determine the meaning of a statute. In cases where a judge uses such tools, the rule of lenity states that ambiguity in a criminal statute should be resolved in favor of the defendant.
Unconstitutional vagueness 
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. No one must risk criminal prosecution merely because he or she cannot reasonably understand what conduct is prohibited under the law.
Examples of Unconstitutional vagueness 
- The Florida Supreme Court, in Franklin v. State, ruled that the state's felony ban on sodomy was unconstitutionally vague because an "average person of common intelligence" could not reasonably know, without speculating, whether "abominable and detestable crime against nature" included oral sex or only anal sex.
- Papachristou v. Jacksonville and Kolender v. Lawson were two Supreme Court cases where the court struck down laws against vagrancy for unconstitutional vagueness; in restricting activities like "loafing," "strolling," or "wandering around from place to place," the law gave arbitrary power to the police and, since people could not reasonably know what sort of conduct is forbidden under the law, could potentially criminalize innocuous everyday activities.
- In Hoffman Estates v. The Flipside, Hoffman Estates, Inc., the Supreme Court considered a pre-enforcement challenge to a municipal ordinance imposing licensing requirements and other restrictions on stores that sold drug paraphernalia. The Court sided with the village, holding that in such a lawsuit the plaintiff must demonstrate that the law would be "impermissibly vague in all its applications."
- The U.S. Supreme Court, in City of Akron v. Akron Center for Reproductive Health, struck down a provision of Akron's abortion law which required that physicians dispose of fetal remains in a "humane and sanitary manner." "Humane" was judged to be unconstitutionally vague as a "definition of conduct subject to criminal prosecution"; the physician could not be certain whether or not his conduct was legal.
- The Mandatory Victim Restitution Act has been ruled to be so imprecise as to be unconstitutional as applied to certain defendants.
- The United States Court of Appeals for the Third Circuit ruled that a supervised release condition prohibiting a defendant from possessing "all forms of pornography, including legal adult pornography" was unconstitutionally vague because it posed a real danger that the prohibition on pornography might ultimately translate to a prohibition on whatever the officer personally found titillating.
See also 
- Overbreadth doctrine
- Plain Language Movement
- Constitutional economics
- Rule according to higher law
- "Vagueness doctrine definition". Cornell University Law School Legal Information Institute. Retrieved 30 December 2012.
- Burrell, Lesley (3 January 2011). "The Right-to-Honest-Services Doctrine—Enron’s Final Victim: Pure Void-for-Vagueness in Skilling v. United States". Loyola of Los Angeles Law Review (Digital Commons at Loyola Marymount University and Loyola Law School) 44 (3): 1289–1306. Retrieved 30 December 2012.
- Connally v. General Const. Co., 269 U.S. 385, 391(1926)
- Hedges v. Obama, 12-cv-00331 (U.S. District Court, Southern District of New York (Manhattan) May 16, 2012).
- Free Legal Encyclopedia: Void for Vagueness Doctrine
- Franklin v. State, Florida Supreme Court, 17 December 1971, accessed 14 July 2011
- Hoffman Estates v. The Flipside, Hoffman Estates, Inc., 455 U.S. 489 (1982), at 495, Marshall, J.
- AKRON v. AKRON CENTER FOR REPRODUCTIVE HEALTH, 462 U.S. 416 (1983)
- United States v. Kemp, 938 F Supp 1554 (ND Ala 1996).
- United States of America v. Ray Donald Loy, 237 F3d 251 (January 4, 2001).
- Chemerinsky, Erwin. (2002). Constitutional Law Principles and Policies, Aspen Publishers, ISBN 0-7355-2428-9.
- Harr, J. Scott and Kären M. Hess. (2004). Constitutional Law and the Criminal Justice System, Wadsworth Publishing, ISBN 0-534-62880-X.