Government is force.
What Really Limits Government?
Force limits government. First, government is limited by the force it has at its disposal. A government whose agents are armed only with truncheons is far more limited than a government whose agents are armed with machine guns, tear gas, and the hydrogen bomb. Second, government is limited by the force its subjects have at their disposal. Finally, a government is limited by the force other governments have at their disposal.
A constitution can limit a government no more than blueprints for a dam can limit a flood. A dam must be built of something concrete, and likewise a government must be held back with force of arms.