a rule that is not sanctioned by the norms of state law but has been applied for a long time by agencies of state power and administration. Constitutional custom is sometimes called constitutional agreement, conventional norm, or constitutional ethic. Constitutional custom is most frequently encountered in Great Britain, the United States, and countries that have adopted the Anglo-Saxon legal system. In Great Britain, for example, supreme executive power legally belongs to the monarch, but by constitutional custom it is exercised by the cabinet. According to constitutional custom the only person whom the king may appoint to the post of prime minister is the leader of the party with a majority in the House of Commons. The cabinets of the United States and India exist only through constitutional custom; they are not provided for by the constitutions of these countries. Bourgeois legal scholars hold that public opinion guarantees the observance of constitutional custom, and therefore these customs are sometimes regarded as nonlegal norms that regulate the application of the norms of state law.
Constitutional custom also exists in the socialist countries, primarily with respect to procedure in representative bodies, for example, the election of the Council of Elders in the chambers of the Supreme Soviet of the USSR.