blanket. It is illegitimate. In 1776, the legally constituted authority in the thirteen colonies was the British Empire, and power to alter the constitutional arrangements in the colonies resided, depending on your point of view, in the British Parliament or in the British Crown. Neither of those authorities had delegated to the Continental Congress the power to issue a Declaration of Independence. Later, in 1781, the first United States constitution came into effect in the form of the Articles of Confederation. Even if you view them as the new grundnorm with an acquired legal legitimacy, those Articles provided that any future change would require the unanimous consent of the state legislatures. Nevertheless, the Articles of Confederation were replaced only eight years later by a different process which did not involve unanimous approval of the state legislatures. The new constitution of 1789 was generally accepted as politically legitimate, and no one would challenge it today. Again, nothing succeeds like success.
These are two examples of a new constitutional order being introduced without legal legitimacy but enjoying general acceptance. The converse situation also can arise, where a constitution has legal legitimacy but little or no political legitimacy. A recent example in our times may be found in the authority which the British Parliament and Government exercised so lawfully, and so ineffectively, over Rhodesia from 1965 to 1980. In 1965 Rhodesia was a self-governing colony of Britain, with wide powers of internal government but with a British-appointed Governor and with the British Parliament having ultimate legislative supremacy. On November 11, 1965, Mr. Ian Smith, the Prime Minister of Rhodesia, issued a unilateral declaration of independence. Although he and his ministers were dismissed by the Governor, they proceeded to adopt a new constitution. On November 16th the British Parliament passed an Act altering Rhodesia’s previous colonial constitution and putting most of the powers of government of Rhodesia directly in the hands of British officials. Meanwhile, back in Rhodesia, Mr. Smith and his colleagues were busily running the country. In London, Orders in Council for the peace, order, and good government of Rhodesia were solemnly being adopted, without the slightest effect in that country. The British government and much of the world said that the Smith regime was illegal. The Judicial Committee of the Privy Council confirmed that opinion. But it made scarcely a bit of difference to Mr. Smith and his government and to the people of Rhodesia who either supported Mr. Smith or acquiesced in his regime.3 While the legally legitimate authority over Rhodesia rested in the United Kingdom Parliament, the effective constitution of Rhodesia was that put in place by the Smith government in 1965.
3. See. e.g., Leigh, “Rhodesia After U.D.I.: Some Aspects of a Peaceful Rebellion.”  Public Law 148; Dias, “Legal Politics: Norms Behind the Grundnorm” (1968) 26 Camb. L.J. 233.