Other countries have little bearing on the legal system of the United States. In the United States the people fought a rebellion to take power, that power is reserved to the people, a small grant of power was given by the people to establish a central government via the Constititution and to grant the power that state governments derive from (although only in a very token sense because colony/state representatives were the actual authors more so than the people they were supposed to represent). It is the founding document and only source of legal authority for the central government. The only exception is within the judicial where a framework was needed for interpreting law and for this the previously English population turned to "common law" largely based on the magna carta.
The system has been heavily corrupted and the central government does many things beyond the scope of Constitutional authority, many of them with the blessing of blatantly incorrect rulings by the Supreme Court, but the Supreme Court can still toss these things out on the basis that they are not within Constitutional authority because that IS the highest law in this country. As for the teeth behind it, there is more than just civil uprising, the military of this nation is sworn to uphold and defend the Constitution.