The long-running argument about the United Kingdom's acceptance of the European Convention on Human Rights (ECHR) took another turn last week with confirmation that a Conservative Government would leave the Convention and the jurisdiction of its supervising court, the European Court of Human Rights.

Confusingly, the ECHR has nothing to do with the European Union, so Brexit had no effect on our participation.

The arguments on both sides have always been passionately expressed, but I have always found the case for staying or leaving finely balanced.

Some of the arguments that have been made I simply don't accept.

The ECHR is not the only meaningful guarantee of human rights in this country and if we left the Convention structures then our courts could do that job perfectly well. They would also continue to be a thorn in the side of Governments when decisions of ministers are unlawful, as they should be.

Leaving the ECHR would not and should not mean that ministers are not constrained.

We would not become Russia or Belarus if we left.

Equally, it is wrong to suggest that leaving the ECHR is simple and consequence-free.

As Lord Wolfson (the Shadow Attorney General) sets out in his first-class advice to the Shadow Cabinet, which has been published and is both a comprehensive and accessible account of the case for leaving, the problems we would face in leaving are largely political and diplomatic rather than legal, but face problems we undoubtedly would.

Lord Wolfson explains that our trade deal with the EU and the Good Friday Agreement in Northern Ireland do not present legal bars to departure, but would present challenges of renegotiation and resolution of potential divergences in the law on either side of the Irish Sea. These remain substantive issues.

There is also the question of what we do to replace the ECHR in domestic law, which requires considerable thought.

If the answer is we replace it with nothing at all, we are likely to see more judge-made law, and it is judge-made law which has prompted many to conclude we must part ways with the ECHR.

If we choose to replace the ECHR with a domestic Bill of Rights or similar, how different will it end up being to the ECHR we have left and, if it is different, might it end up as an even more extensive human rights instrument for lawyers to get their teeth into than the ECHR was?

All of this has yet to be worked through.

I have however come to the conclusion that we will almost certainly have to leave the ECHR, for two linked reasons.

First, the issue of migration, and in particular illegal migration, is likely to grow as a salient political issue and as a real challenge for governments throughout the developed world.

Mass migrations, driven by war and by climate change, are going to oblige every country which will be a destination of choice to find a way of controlling immigration effectively.

An international convention which presents unreasonable obstacles to even rational and decent policies will prove intolerable, and we are already seeing signs of this.

Extensive interpretations of Articles of the Convention, Article 8 which protects the right to a private and family life for example, has obstructed the removal of individuals who present clear threats to our society, in the UK and elsewhere.

Efforts to persuade the court to take a more balanced view by a number of signatory countries, not just the UK, are being made now, and if they were to succeed the position may be different, but I am not optimistic.

This is because the Court in Strasbourg has also shown a recent willingness to take a more, not less extensive view of the rights the convention protects, and indeed of those who may litigate those rights.

The most striking example is the so-called Klimaseniorinnen case against Switzerland last year, which I have re-read in the light of recent events. In that case, the Strasbourg court concluded that Article 8 rights could be infringed by their government's inadequate performance (as judged by the court), in protecting its citizens from climate change.

I doubt this is what the drafters of the ECHR had in mind when they wrote Article 8.

In addition the court in that case decided that the requirement that only those whose rights were directly affected and who had suffered harm could bring a case under the convention should be loosened so that pressure groups can bring cases too.

These changes represent in my view considerable overreach on the part of the court and indicate that the court sees the development of its role as a one-way ratchet.

If it is legitimate for the Strasbourg Court to pronounce on the effectiveness of environmental policy because its consequences may affect rights, why not health policy? Or nuclear policy? Or defence policy?

This is a version of human rights law I think the UK did not sign up for and cannot accept. If there is no sign of a change in this approach, I cannot see how a proper balance between political accountability and judicial oversight as the British would understand it can be maintained, and our continued adherence to the ECHR, requiring as it does acceptance of the Strasbourg Court's interpretation of the Convention, would become impossible.