The Separation of Powers

Separation of Powers was first developed by John Locke in his Second Treatise of Civil Government (1690). It was developed further by Montesquieu in his book, De l'Esprit des Lois (1748). 

John Locke, Second Treatise of Civil Government (1690) - defined tyranny as the exercise of wide discretionary and arbitrary power by those in government for their own private advantage. 

Montesquieu, De l'Esprit des Lois (1748) - the loss of individual liberty would be inevitable where there is no separation of powers. The government could make tyrannical laws and execute them in a tyrannical manner. The danger is that laws would be applied in an arbitrary way which undermines personal liberty if lawyers were also legislators and members of the executive. They might also apply the law in a way which was violent and oppressive. 

R v Liyanage (1967) - the Privy Council had to decide whether measures passed under the Criminal Law (Special Provisions) Act, No 1 of 1962 by the Parliament of Ceylon (now Sri Lanka) went against the constitution of the commonwealth country. They found that the Act was unconstitutional, as the legislative had unlawfully exercised a function that belonged to the judiciary. Although the constitution did not say so expressly, there was an implied adherence to the separation of powers in the form of an intention to secure the freedom of the judiciary from political, legislative and executive control. 

R (on the application of Anderson) v Secretary of State for the Home Office (2003) - Lord Steyn used the separation of powers to assert that a decision to punish an offender with a term of imprisonment should be made by the courts - the only recognised exception is the ancient power of Parliament to imprison those who are held to be in contempt of Parliament (based on the medieval principle that Parliament may act as a court of justice). Lord Steyn said that the UK constitution has never embraced a rigid doctrine of the separation of powers. In terms of legal formality the monarch, as the head of state, is the head of the executive, the legislature, and the judiciary. The Prime Minister, the members of the Cabinet, and all the other Ministers of the Crown are members of the executive. They are also members of Parliament. If the organs and functions of government within the UK were organised strictly according to the doctrine of separation of powers the Prime Minister, the members of the Cabinet, and all the other Ministers of the Crown would not be permitted to be members of Parliament. The monarch too would not be permitted to be part of the legislature or have any part to play in the appointment of judges. 

Matthews v Ministry of Defence (2003) - This was a negligence claim involving considerations of Article 6 European Convention on Human Rights and Fundamental Freedoms. Lord Hoffman used the separation of powers to assert that the executive must never be able to order a court to dismiss a case…