James Dobson is a Researcher at Bright Blue.

The Prime Minister’s scepticism of the European Convention on Human Rights (ECHR) is well known. During the EU referendum campaign, she called for the UK to withdraw from the ECHR. But, thankfully, in her campaign to become the leader of the Conservative Party, she promised MPs that she would drop this policy aim. It is essential that she keeps her word.

The Prime Minister has also been clear that just because we are leaving the European Union, it does not mean we are leaving Europe. Indeed, Brexit should not mean abandoning elements of Europe which are in the British national interest.

That is why Bright Blue is, today, launching its new petition to ensure the Prime Minister commits Britain to remaining a signatory of the ECHR after Brexit. This is one of over 60 policies that Bright Blue will be recommending at the forthcoming launch of the final report from our year-long human rights inquiry, which is led by a commission including former Cabinet Ministers Maria Miller MP, Dominic Grieve QC MP and Caroline Spelman MP.

The ECHR was drafted and championed by Conservatives after World War Two. The former Conservative Home Secretary, Sir David Maxwell Fyfe – then a prosecutor at the Nuremberg Trials – was a co-author of the Convention. Sir Winston Churchill was one of its keenest advocates. It exported English common law across the European Continent.

The ECHR lists both qualified and unqualified rights that protect individuals from an overreaching state and undue power: freedom from torture and servitude, as well as the right to a fair trial, to free expression and to privacy.

There are 47 countries who are signatories of the ECHR, many of them more oppressive countries than Britain. It is true that that such countries are often slow to implement the judgments of the Strasbourg Court. But decisions do eventually get implemented. Victims do get compensated. The judgements of the European Court of Human Rights have strengthened human rights in Britain, as well as in more oppressive countries. Those judgments include the rights of gay, lesbian, bisexual and transgender people, the rights of the media against state censorship, more effective prosecution of domestic violence, and the rights of illegitimate children. Polling shows the British public are in favour of most of the rights enshrined in the articles in the ECHR.

It is vital, particularly as authoritarian leaders are becoming more popular and powerful across the Western world, that the home of human rights – the United Kingdom – remains a leading advocate of a rules-based international system and a proud signatory of the ECHR.

There would be some practical problems with withdrawing from the ECHR, too. Britain’s impending withdrawal from the European Union, especially the customs union, has raised the prospect of a hard border between Northern Ireland and the Republic of Ireland. The Secretary of State for Exiting the European Union, David Davis MP, has rightly made a soft border a key priority for Brexit negotiations, but this has not stopped Sinn Féin – who achieved their best election result in the party’s Northern Irish history earlier this month – calling for a referendum on leaving the UK and and uniting with the Republic of Ireland.

Withdrawal from the ECHR risks damaging the unionist cause further. The ECHR is central to the Northern Ireland peace process. The Good Friday Agreement – the peace deal which brought an end to the Troubles in Northern Ireland, and took two different Prime Minister’s five years to negotiate – explicitly requires that the ECHR has ongoing legal effect in Northern Ireland. Withdrawal from the ECHR would therefore require the UK government to renegotiate substantial parts of the Good Friday Agreement.

This would be fraught with difficulty. The European Court of Human Rights features heavily in the Good Friday Agreement because it is viewed as an impartial court which does not favour the Unionists or, indeed, the Republicans. In any renegotiation, the UK government would have to replace the ECHR with another court. The only obvious candidate for this would be the UK’s Supreme Court. The Republicans could be sceptical that the Supreme Court will be truly impartial. If the renegotiations did make it past this point then they would almost certainly need to be approved by the public in Northern Ireland and in the Republic of Ireland through referendums – as was done in 1998.

Scotland and Wales pose problems too. Both the Scotland Act (1998) and Government of Wales Act (2006) require the devolved Parliament to make law which is compliant with the ECHR. So to un-incorporate the ECHR completely from British law, these devolution acts would have to be repealed or amended. But the convention in Parliament – the Sewel Convention – is that Westminster will only legislate with regard to devolved matters when they have the consent of the devolved parliaments. It is highly unlikely that the devolved Parliaments would give such consent in respect of the ECHR. Thus, the only forward for the UK government would be to break the Sewel Convention and give more grievances for the Scottish nationalists to cite in their campaign for independence.

The ECHR has coincided with a period of unprecedented peace across Europe. It’s value in both the UK and abroad should not be underestimated. The ECHR is also crucial to the survival of the union. To attempt to renegotiate the Good Friday Agreement now would be simply reckless. Providing nationalists with further grievances to cite in Scotland would also be careless. The UK has been central to the success of the ECHR: the Prime Minister should show that the UK is leaving the EU and not Europe, and commit a future Conservative Government after Brexit to remaining a proud signatory of the ECHR.