No free man shall be seized or imprisoned, or stripped of his rights or possessions, or outlawed or exiled, nor will we proceed with force against him except by the lawful judgement of his equals or by the law of the land. To no one will we sell, to no one deny or delay right or justice.
Magna Carta - a Common Law document - came into being in 1215; a contract between the knights, barons, clergy, townspeople and the King. Magna Carta affirmed the right of the People to such things as trial by jury, and protection from excessive fines.
In 1297 the Model Parliament confirmed Magna Carta in statute law. Much of this statute has since been repealed. Yet while Parliament can repeal or amend any Act of Parliament (statute), Parliament was not a party to the original Common Law contract, and cannot, therefore, amend or repeal it lawfully, and thus its original provisions remain intact.
Constitutional Convention 1215
Lord Blackstone is most famous for having written his Commentaries on the Laws of England, but he also wrote a book on Magna Carta. This is what he had to say of the circumstances leading to the constitutional convention which led to Magna Carta:
On the 5th May, the barons, having chosen as their leader, Robert Fitzwalter ... performed the solemn fuedal ceremony of diffidatio, or renunciation of their fealty and homage, a formality indispensible before vassals could, without infamy, wage war upon their feudal overlord. Absolved of their allegance ... they marched on London.
What this demonstrates is that having taken an oath of allegiance which one might assume is for life, is not, and so allegiance can be withdrawn if the Monarch is in breach of their contract with the people.
It was on the 15th June, then, in the year 1215, that the conference began between John, supported by a slender following of half-hearted magnates, upon the one side, and the mail-clad barons, back by a multitude of well-armed knights, upon the other. The conference lasted for eight days, from Monday of one week till Tuesday of the next. On Monday the 15th, John set seal to the demands presented to him by the barons, accepting every one of their "Articles," with the additional "Forma Securitatis" or executive clause, vesting in twenty-five of their number full authority to constrain King John by force to observe its provisions.
Right to Rebel
That "full authority to constrain ... by force" is one of the key features of Magna Carta: our right to rebel should the government of the day be operating outside it's lawful authority.
Article 61 says:
Since we have granted all these things for God, for the better ordering of our kingdom, and to allay the discord that has arisen between us and our barons, and since we desire that they shall be enjoyed in their entirety, with lasting strength, for ever, we give and grant the barons the following security:
The barons shall elect twenty-five of their number to keep, and cause to be observed with all their might, the peace and liberties granted and confirmed to them by this charter ...
The baron's committee is formed whenever the people petition them with their grievances, and this was done in 1999.
Article 61 continues:
If we, our chief justice, our officials, or any of our servants offend in any respect against and man, or transgress any of the articles of the peace or of this security, and the offence is made known to four of the said twenty-five barons, they shall come to us - or in our absence from the kingdom to the chief justice - to declare it and claim immediate redress by seizing our castles, lands, possessions, or anything else save only our own person and those of the queen and our children, until they have secured such redress as they have determined upon. Having secured the redress, they may then resume their normal obedience to us ...
The phrase "until they have secured such redress as they have determined upon" gives the authorty for a constitutional convention. There have been three such conventions in the last 800 years.
The first was at Runnymede when Magna Carta was signed. The barons were the final court of appeal, as they still are under our Common Law, and determinations made by the barons have the status of a legal judgement. So the barons met at Windsor Castle, with the full support of the people who had risen up, and Magna Carta was the result.
Article 61 continues:
Any man who so desires may take an oath to obey the commands of the twenty=five barons for the achievement of these end, and to join with them in assailing us to the utmost of his power. We give public and free permission to take this oath to any man who so desires, and at no time will we prohibit and man from taking it. Indeed, we will compel any of our subjects who are unwilling to take it to swear it at our command.
In other words, it is our duty to step in and require the Monarch to uphold their contract with the people. Sovereignty lies with the people and the Monarch is bound by that oath to hold an out-of-control government to account.