Unconstitutional

adj. not constitutional, not authorized by the constitution, not in keeping with the constitution

Constitutionality is the status of a law , a procedure, or an act's accordance with the laws or guidelines set forth in the applicable constitution. When one of these directly violates the constitution it is unconstitutional. All the rest are considered constitutional until declared otherwise.An act (or statute) which is enacted as law either by the council of a city or county, by the legislature of a state or province, or by a national legislature, may be declared unconstitutional. When the proper court determines that the act in question conflicts with the constitution, it finds that law unconstitutional and declares it void in whole or in part. This is called judicial review. The portion of the law that is declared void is considered to be struck down, or the entire statute is considered to be struck from the statute books.
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Adjective
1. not consistent with or according to a constitution; contrary to the U.S. Constitution
(antonym) constitutional

(a.)
Not constitutional; not according to, or consistent with, the terms of a constitution of government; contrary to the constitution; as, an unconstitutional law, or act of an officer.
  

That which is contrary to the Constitution.

When an act of the legislature is repugnant or contrary to the Constitution, it is, ipso facto, void.

The courts have the power, and it is their duty, when an act is unconstitutional, to declare it to be so; but this will not be done except in a clear case and, as an additional guard against error, the Supreme Court of the United States refuses to take up a case involving Constitutional questions, when the court is not full.
   

This entry contains material from Bouvier's Legal Dictionary, a work published in the 1850's.