HUMAN rights may be fundamental, but they change over time. Laws on these islands have insisted on the right to a fair trial for centuries, but what we have understood fairness to require changes with the generations.

The US Constitution’s prohibition of “cruel and unusual punishments” has been a feature of American law for more than 200 years, but what courts think “cruel and unusual” may mean develops, just as society’s broader understanding of such open-ended terms evolves. The law may freeze words in a certain moment in time, but words are not fossils. They have lives of their own.

And so it is with the right to life. As fundamental a human right as one could conceive, for sure, yet one whose meaning and application is contested, raising deep questions of morality and belief, and requiring to be treated in the most careful and sympathetic way. This is the last area where one should rush to judgement. It is not merely the other side that must be heard: it is every side.

From the 1960s to the 1990s it was regarding the beginning of life that arguments raged over the right to life; in the present century it is the end of life. In the United Kingdom we dealt with the law of abortion relatively well – it did not divide society in the toxic manner that has so marked the United States in recent decades. Now we must rise to the challenge again, in the context of assisted dying.

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The question is this: should those with terminal illness, facing a long and potentially painful death, have the right to medical assistance in ending their lives? As the law stands in the UK they have no such right. Assisting someone in the act of suicide is a criminal offence. This, as human rights lawyers like to say, is a blanket ban. It admits of no exceptions.

Some say: this is what the right to life requires. But others say: the right to life is not the only human right at stake here. There is also the right to privacy, with the right to be treated at all times with respect and dignity which that right now entails. Kevin McKenna made the powerful argument in these pages on Monday that, if we are going to start to make decisions about dying on the basis of “dignity”, should we not also be making decisions about the conditions in which people live on that basis?

Whether we enact into our law a right to medically-assisted suicide is a fraught question not because it divides progressives from conservatives. It is a question that divides liberals (who believe in choice) from liberals (who believe in the sanctity of life and who worry about the duress and coercion that all too often control choice).

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That is the key issue which any proponent of a law on assisted dying will have to answer – how can we ensure that the decision someone makes to seek their doctor’s help in ending their life is a genuinely free choice?

That these matters are now coming to Holyrood is a very good thing. As in the abortion debates in the 1960s – and whatever we think of its outcome –parliaments are where this debate should happen. A parliament, in this decade, which refuses to deliberate upon the question of assisted dying is a parliament which is failing in its duty.

The Supreme Court of Canada ruled in 2015 that the blanket ban on assisted suicide in Canadian law was contrary to the Canadian Charter of Rights. It gave the federal parliament in Ottawa 12 months to enact legislation to fix it. The UK Supreme Court came perilously close in 2014 to making a similar ruling for England and Wales. Instead, it pulled back, indicating that while the matter really was one for parliament to legislate about, rather than for the courts to rule on, the courts would feel compelled to act if parliament sat on its hands and did nothing.

The courts in the UK stayed out of the abortion debates because parliament acted. Our abortion laws are creatures of legislation, not of case law. But my sense is that our courts will not stay out of the debate on assisted dying for much longer. They will follow Canada’s lead and force Holyrood and Westminster to act if our parliaments do not take the initiative first.

This is not to load the dice in favour of one outcome or another. It does not follow that, just because a parliament considers a Bill, the law will change. A decision, after due deliberation, not to change the law is every bit as valid as a decision that the law requires amendment. But the debate has to happen and it is so much better that it unfolds on parliament’s terms and not because an appeal court has forced the issue.

The burden on our lawmakers is onerous. Legislating on issues of fundamental rights is not easy and Holyrood has not always got it right in the past. Perhaps, therefore, parliament should not have the last word. Last year New Zealand enacted into a law a limited right to assisted dying in its End of Life Choice Act. That Act came into force only because it was endorsed in a popular referendum. The referendum was binding – had the result gone the other way the Act would have fallen.

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In considering once again the law on assisted dying in Scotland, Holyrood should explore the ways in which popular, participatory democracy can be part of our process of deciding what, as a country, we want to do. We could have a citizens’ assembly on the topic. Or we could follow New Zealand. Let our parliament debate the issues in full and at length – and then let the people decide. And, for as long as we can, let us keep the courts out of it.

Our columns are a platform for writers to express their opinions. They do not necessarily represent the views of The Herald.