Constitutional law is a body of law which defines the role, powers, and structure of different entities within a state, namely, the executive, the parliament or legislature, and the judiciary; as well as the basic rights of citizens and, in federal countries such as the United States and Canada, the relationship between the central government and state, provincial, or territorial governments.

The Constitution of the Republic of Singapore is the supreme law of Singapore. A written constitution, the text which took effect on 9 August 1965 is derived from the Constitution of the State of Singapore 1963, provisions of the Federal Constitution of Malaysia made applicable to Singapore by the Republic of Singapore Independence Act 1965, and the Republic of Singapore Independence Act itself. The text of the Constitution is one of the legally binding sources of constitutional law in Singapore, the others being judicial interpretations of the Constitution, and certain other statutes. Non-binding sources are influences on constitutional law such as soft law, constitutional conventions, and public international law.