Since I am the one who inspired this thread, I think I should make things clear. You made the following statement pertaining to the pepper spraying incident that took place yesterday:
That is false. The police do not refer to the US Constitution to determine what is and isn't legal. They refer to the statutes from a city, state, federal, etc.. Those are the laws we all are expected to follow, and police are duty bound to enforce.
The constitution is not a set of laws, but rather a set of rules and guidelines used to fashion our laws. Our laws must be in compliance with the constitution, otherwise they are not laws. Many laws throughout our history have been made and enforced that violate the constitution, but because they were not challenged for their constitutionality at the time of passing, they were considered legal and were enforced. When people challenge the constitutionality of a law, it is then the job of our judicial system to determine it's compliance with the constitution.
For example... You can not say what you want, anywhere you want, at any time you want, and claim the legal right to do so under the constitution's right to free speech. If that were the case, you could break into my home, enter my bedroom at 2am and start reading the bible to me because I didn't attend church, and I would have no legal recourse.