Constitutional monarchy (or limited monarchy) is a form of government in which a monarch acts as head of state within the parameters of a constitution, whether it be a written, uncodified, or blended constitution. This form of government differs from absolute monarchy in which an absolute monarch serves as the source of power in the state and is not legally bound by any constitution and has the powers to regulate his or her respective government.

Most constitutional monarchies employ a parliamentary system in which the monarch may have strictly ceremonial duties or may have reserve powers, depending on the constitution. Under most modern constitutional monarchies there is also a prime minister who is the head of government and exercises effective political power. There also exist today several federal constitutional monarchies. In these countries, each subdivision has a distinct government and head of government, but all subdivisions share a monarch who is head of state of the federation as a united whole.

Professor Adam Tomkins is a British legal scholar and John Millar Professor of Public Law at the School of Law of the University of Glasgow.

Tomkins was educated at the University of East Anglia (LL.B.) and the London School of Economics (LL.M.). He taught at the School of Law of King’s College London between 1991 and 2000 and became a fellow at St Catherine's College, Oxford in 2000, before being elected to the John Millar Chair of Law at Glasgow in 2003. His research interests lie in constitutional theory and history, British, EU and comparative constitutional law, and republicanism.

Professor Tomkins has published seven books in the areas of constitutional, administrative and European Union law, including two, Public Law (2003) and British Government and the Constitution (2007, with Colin Turpin), which are amongst the most widely used by law students in the United Kingdom.

Professor Tomkins is a member of the group, Republic, a British republican organisation advocating the replacement of the monarchy with a democratically-elected head of state, and has published Our Republican Constitution, a republican re-interpretation of the United Kingdom's constitution which claims that the constitution is deeply influenced by republican principles, despite its monarchic nature.