In political science, a constitutional crisis is a problem or conflict in the function of a government that the political constitution or other fundamental governing law is perceived to be unable to resolve. There are several variations to this definition. For instance, one describes it as the crisis that arises out of the failure, or at least a strong risk of failure, of a constitution to perform its central functions. The crisis may arise from a variety of possible causes. For example, a government may want to pass a law contrary to its constitution; the constitution may fail to provide a clear answer for a specific situation; the constitution may be clear but it may be politically infeasible to follow it; the government institutions themselves may falter or fail to live up to what the law prescribes them to be; or officials in the government may justify avoiding dealing with a serious problem based on narrow interpretations of the law. Specific examples include the South African Coloured vote constitutional crisis in the 1950s, the secession of the southern U.S. states in 1860 and 1861, the dismissal of the Australian federal government in 1975 and the 2007 Ukrainian crisis. While the United Kingdom of Great Britain and Northern Ireland does not have a codified constitution, it is deemed to have an uncodified one, and issues and crises in the UK and its constituent countries are described as constitutional crises.

The Coloured vote constitutional crisis, also known as the Coloured vote case, was a constitutional crisis that occurred in the Union of South Africa during the 1950s as the result of an attempt by the Nationalist government to remove coloured voters in the Union's Cape Province from the common voters' rolls. It developed into a dispute between the judiciary and the other branches of government over the power of Parliament to amend an entrenched clause in the South Africa Act and the power of the Appellate Division to overturn the amendment as unconstitutional. The crisis ended when the government enlarged the Senate and altered its method of election, allowing the amendment to be successfully enacted.