The duty to ENFORCE the constitution lies with We, the people exercising our 1st and 2nd amendment rights. That is why it is written from the perspective of "We, the people. The duty of the executive and legislative branches is to DEFEND the constitution by providing effectively for the common defense, and not knowingly passing any laws that contradict it. The duty of the Judicial branch (SCOTUS) is to interpret the constitution sufficiently to settle any questions that might arise. Activist judges and Justices have blurred the line between branches, but the actual responsibility to hold governments feet to the fire and MAKE them obey the Constitution lies with "We the people".