separation of powers

   The idea that the legislative power, the executive power and the judicial power of any state should be placed in separate hands, through the creation of three independent branches of government. The doctrine was advocated by the French Enlightenment thinker Montesquieu in the eighteenth century in his classic book L’Esprit des lois. He felt that it was desirable to keep the three branches separate, for this would provide a safeguard against too much concentration of power in one single authority. By fragmenting power, liberty could be defended and tyranny kept at bay. He based his assessment on his understanding of the British system, and felt that in Britain good administration derived from the fact that no one person or body could control the three arms. Each could exercise control over the other. Montesquieu’s ideas much influenced the writing of the American Constitution.

   In Britain there is not the clear separation of powers which Montesquieu detected. In reality there is a considerable overlap between the three branches. For instance: the heads of the executive (the Prime Minister and members of the Cabinet) are drawn from, and sit in, Parliament; some judicial functions are exercised by an elected politician, the Home Secretary (for example, the prerogative of mercy) and leading members of the judiciary are appointed by the Prime Minister (for example, the law lords, who constitute the final court of appeal and yet sit in the legislature); and the Lord Chancellor has powers in all three branch of Government (he is a member of the Cabinet, the senior figure in the judiciary and sits in the House of Lords where he acts as Speaker). These judicial aspects have been addressed in the Constitutional Reform Act (2005).