At the end of the
Thirty Years’ War in 1648, this agreement gave individual
princes the right to choose the official
religion of their realm. As such, it was one of the first, and most important, documents to declare the idea of the
sovereignty of states.
State
sovereignty establishes that it is the ruler of the state that has supreme
political authority. This allows them to claim supremacy within the boundaries of their realm and absolved them of the need to consult with a higher authority. Legally, the treaty entrenched the idea of the
state as the sole actor with the right to the
legitimate use of force. The basis of this is in the reciprocal recognition of this right by all states. Political legitimacy was beginning to be seen in
secular rather than religious terms: a development along the path to
liberal democracy.
Another major element of the
Westphalian System is the idea of
collective security. Whenever a state displayed blatant aggression towards another, all of the others were to unite in opposition to the aggressor in order to restore the
status quo. This multipolar
balance of power is considered to have endured until the end of
WWII.