Loyal opposition
Loyal Opposition is the concept that one can be opposed to the actions of the government of the day without being opposed to the constitution of the political system.
In the United Kingdom and other Commonwealth countries the leader of the largest minority party in Parliament is termed "The Leader of Her Majesty's Loyal Opposition". Their constitutional function is to scrutinise Government legislation and actions. While opposing Her Majesty's Government at every turn, he is not opposed to Her Majesty's right to the throne.
This is an important difference between the developed constitutional monarchy of the 18th century onwards and the previous squabbles between competing candidates for the throne supported by different religious and economic groups.
Most developed political systems have a similar concept though without the British ritual jargon. Parties acknowledge the constitutional system in which they operate, including the procedures to change the constitution itself. A change of government can take place without revolution and without revolutionary implications.
See also:
