It would be folly to kill off Magna Carta’s closest living relative.

Of all the events taking place during my year as president of the Law Society, the 800th anniversary of the sealing of Magna Carta is undoubtedly the one of greatest constitutional significance. It is a valuable opportunity to remind ourselves of the importance of the rule of law – a central theme of last week’s Global Law Summit – as being the basis of a free, fair and prosperous society.

Magna Carta is universally recognised as being the foundation stone that supports the fundamental civil liberties enjoyed by democratic countries across the world. In fact, many see the ‘Great Charter’ as the starting point for human rights, the most fundamental of documents in the protection of the people from the powers of government.

This year also sees a general election. As part of its election campaign the Conservative party has pledged to ‘scrap’ the Human Rights Act (HRA) and replace it with a Bill of Rights. At the same time, in its current position as the leading party, it has been instrumental in the promotion and celebration of Magna Carta in its 800th year. Is this a troubling contradiction?

For the last two years I have been a member of the Magna Carta 800th Committee. We have described this historic document as being ‘the most valuable export of Great Britain to the rest of the world’. Indeed, having enshrined the rule of law in our society, for centuries it has influenced constitutional thinking worldwide including in France, Germany, Japan, the US, India, Latin America and Africa.

Magna Carta was central to both the US Declaration of Independence and its constitution, as well as to the UN Declaration of Human Rights in 1948. Speaking at the UN general assembly as the declaration was submitted, Eleanor Roosevelt said: ‘We stand today at the threshold of a great event both in the life of the United Nations and in the life of mankind. This declaration may well become the international Magna Carta for all men everywhere.’

Magna Carta is far from being relevant purely in history lessons. It is being used continually, 800 years after its creation, to defend some of the most prominent human rights battles in the most modern of democratic societies. For example, more than 200 writs of habeas corpus have been submitted on behalf of detainees at Guantanamo Bay.

Habeas corpus, or ‘the great writ’, is a legal instrument first guaranteed following the sealing of Magna Carta, its purpose being to prevent the state from holding prisoners in extrajudicial detention. Now in the (slow) process of being closed, the challenges against the legality of Guantanamo Bay continue to focus upon the violation of these most basic of human rights principles.

Today, in our own jurisdiction, it is the HRA, along with the UN Declaration of Human Rights, that is the closest descendant of Magna Carta.

The HRA ensures that the rights included in the European Convention on Human Rights are enshrined in UK law. The convention was, of course, established following the second world war to protect the rights of people over the powers of governments. It was designed to be used by the young and the elderly, the rich and the poor, British citizens and foreign nationals, prisoners and the public.

We will, hopefully, never need to rely upon it, but every year there are hundreds of people who do. The Law Society is proud of the universal protection the HRA ensures, of the UK’s role in the creation of an EU-wide Court of Human Rights, and of the decisions made by that court. We believe that plans to replace it could result in a diminution of this universal protection and potentially be an attack upon the principles of Magna Carta itself.

But it is not just the HRA that is being held up by the weight of Magna Carta. In January, Lord Pannick QC referred to the Great Charter in the House of Lords while criticising government plans to limit judicial review. Part 4 of the Criminal Justice and Courts Bill will make it more difficult to challenge unlawful decision-making by government and public bodies. When they have behaved unlawfully, it is surely right that the courts should be able to say so. After all, it is a right that can be traced back to the provisions of that 1215 document.

Another legal concern relating to fundamental rights became prominent in the UK last month. The government announced plans to introduce legislation to regulate the use of pre-charge extended bail – specifically to limit it being extended beyond a 28-day limit. Placing a person on unlimited bail is seen by many as a violation of the principle outlined in article 39 of Magna Carta, that ‘no freemen shall be taken or imprisoned or disseised or exiled or in any way destroyed, nor will we go upon him nor send upon him, except by the lawful judgment of his peers or by the law of the land’.

Promoting and supporting Magna Carta as part of our commitment to the rule of law and access to justice has been – and will remain – a key priority of my year as president. This is why we will be both celebrating and commemorating this important anniversary. We have already called on our members for HRA case studies.

The Graham Turnbull human rights essay competition has a Magna Carta theme. Upcoming events include: a lecture on 15 March, ‘The Life and Times of the Human Rights Act’ with Jonathan Cooper and Lord Black of Brentwood; a speech by the master of the rolls Lord Dyson on 22 April; Magna Carta Day in June; and a continued defence of the need for the HRA in the coming months.

In this 800th year since the sealing of this great document, we are concerned that the HRA, our closest relative of the document, faces dissolution. As the world looks to the UK as the forerunner of human rights, dilution of the rights of our citizens does not set a good example. Does it undermine our moral authority to speak up against abuses elsewhere? Does it allow other countries to justify their misconduct by pointing to our own less clear example?

Human rights should never be used as a political tool. Any changes should broaden guarantees of rights rather than seek to limit them – especially in a year when we are celebrating the birth of our fundamental freedoms. It is surely what the remembrance of Runnymede deserves.

Andrew Caplen is president of the Law Society