A doctrine derived from the DUE PROCESS CLAUSES of the FIFTH and FOURTEENTH AMENDMENTS to the U.S. Constitution that requires criminal laws to be drafted in language that is clear enough for the average person to comprehend.
If a person of ordinary intelligence cannot determine what persons are regulated, what conduct is prohibited, or what punishment may be imposed under a particular law, then the law will be deemed unconstitutionally vague. The U.S. Supreme Court has said that no one may be required at peril of life, liberty, or property to speculate as to the meaning of a penal law. Everyone is entitled to know what the government commands or forbids.
The void for vagueness doctrine advances four underlying policies. First, the doctrine encourages the government to clearly distinguish conduct that is lawful from that which is unlawful. Under the Due Process Clauses, individuals must be given adequate notice of their legal obligations so they can govern their behavior accordingly. When individuals are left uncertain by the wording of an imprecise statute, the law becomes a standardless trap for the unwary.
Second, the void for vagueness doctrine curbs the *ARBITRARY and discriminatory enforcement of criminal statutes. Penal laws must be understood not only by those persons who are required to obey them but by those persons who are charged with the duty of enforcing them. Statutes that do not carefully outline detailed procedures by which police officers may perform an investigation, conduct a search, or make an arrest confer wide discretion upon each officer to act as he or she sees fit. Precisely worded statutes are intended to confine an officer's activities to the letter of the law.
* The term arbitrary describes a course of action or a decision that is not based on reason or judgment but on personal will or discretion without regard to rules or standards.
An arbitrary decision is one made without regard for the facts and circumstances presented, and it connotes a disregard of the evidence. In many instances, the term implies an element of bad faith, and it may be used synonymously with tyrannical or despotic. http://law.jrank.org/pages/4415/Arbitrary.html
http://law.jrank.org/pages/11152/Void-Vagueness-Doctrine.html
