A law that is constitutional is a fundamental principal that is in the framework of a constitution. The society must conform to this law as it provides the limitations on the functions of different departments.
A law that is constitutional is one that does not violate the constitution of a state or of the USA. The Supreme Court of the USA is the final decider of whether or not a law is constitutional. Anything can be made a law but it can not be enforced if the Supreme Court has declared it to be unconstitutional. When a majority of Supreme Court judges (5 out of a total of nine judges) who believe that the constitution is not the supreme law of the USA are appointed to the supreme court by the president(s), the US Constitution will no longer be the supreme law of the USA. Instead, the supreme law of the USA will be that which will be ruled by a majority of the nine supreme court judges. When this happens, you can(over a period of time) kiss your freedom of speech, freedom of religion, right to own a gun and separation of church and state good bye. Please read the constitution and vote for people who believe the Constitution is the supreme law of the USA. They include Liberterians and constitutional conservatives.