Yes, the final arbitors of the Constitution are the people themselves (that would be us). This information comes from Federalist Paper Number 44.
"In the first instance, the success of the usurpation will depend on the executive and judiciary departments, which are to expound and give effect to the legislative acts; and in the last resort a remedy must be obtained from the people who can, by the election of more faithful representatives, annul the acts of the usurpers. The truth is, that this ultimate redress may be more confided in against unconstitutional acts of the federal than of the State legislatures, for this plain reason, that as every such act of the former will be an invasion of the rights of the latter, these will be ever ready to mark the innovation, to sound the alarm to the people, and to exert their local influence in effecting a change of federal representatives."
Madison says that we as voters set the limits for Congress, and if Congress takes it upon themselves to exceed the limits which are set, we elect new representatives. Thus, we are all bound by the same set of laws.