A constitutional monarchy is a form of government established under a constitutional system which acknowledges a hereditary or elected monarch as head of state. Modern constitutional monarchies usually implement the concept of trias politica, and have the monarch as the (symbolic) head of the executive branch. Where a monarch holds absolute power, it is known as an absolute monarchy.
Today, constitutional monarchy is almost always combined with representative democracy, and represents theories of sovereignty which place sovereignty in the hands of the people, and those that see a role for tradition in the theory of government. Though the king or queen may be regarded as the government's symbolic head, it is the Prime Minister, whose power derives directly or indirectly from elections, who actually governs the country.
Although current constitutional monarchies are mostly representative democracies, this has not always historically been the case. There have been monarchies which have coexisted with constitutions which were fascist (or quasi-fascist), as was the case in Italy, Japan and Spain, or those in which the government is run as a military dictatorship, as was the case in Thailand.
Some constitutional monarchies are hereditary; others, such as that of Malaysia are elective monarchies.
Constitutionalmonarchy is a form of government in which a king or queen acts as Head of State, while the ability to make and pass legislation resides with an elected Parliament.
The constitutionalmonarchy we know today really developed in the eighteenth and nineteenth centuries, as day-to-day power came to be exercised by Ministers in Cabinet, and by Parliaments elected by a steadily-widening electorate.
Bagehot's views of how monarchy works proved influential, and by the reign of King George V, the principle of constitutionalmonarchy was firmly established in Britain.
Today, constitutionalmonarchy is almost always combined with representative democracy, and represents a compromise between theories of sovereignty which place sovereignty in the hands of the people, and those that see a role for tradition in the theory of government.
The concept of constitutionalmonarchy owes its origin to the absolutemonarchies of the later Middle Ages, where governmental authority was exercised by the monarch and his (or in rare occasions her) government.
It is said in constitutionalmonarchies that the monarch "reigns but does not rule." Most modern constitutionalmonarchies owe their origins to systems in which the monarch not merely reigned but governed, as in the absolutemonarchies which replaced aristocratic systems in the Renaissance.