“The only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others,” wrote John Stuart Mill in his essay On Liberty, which has come to underpin liberal thought. The philosopher went on: “Over himself, over his own body and mind, the individual is sovereign.” Though this standpoint is accepted in many parts of the law, in one crucial regard it is not: a terminally ill and suffering patient cannot be offered direct help in dying with dignity at a time or place of their choice. Those who break the law by assisting can face up to 14 years in prison.

This threat hangs over the grieving families who travel from the UK to Switzerland for an assisted death: one each week. There are thought to be scores of cases in Britain where the terminally ill take their own lives in awful circumstances. The issue is one that brushes everyone; we all have to experience the death of people about whom we care deeply. We all have to contemplate our own death.

At present the director of public prosecutions, an individual who holds office for a term of five years, effectively acts like a judge: deciding whether or not a person is guilty of hastening the death of terminally ill patients who wish to spare themselves and their loved ones from the final, crippling stages of degenerating health. It is the DPP who determines, via their own guidelines, whether or not a family member was motivated by compassion rather than pecuniary gain; whether or not the assistance was minor; whether or not they had reluctantly helped.

This cannot be right. Courts need laws that draw the boundaries clearly between what is right and what is wrong. It cannot be up to the DPP to decide. In 2015 lawmakers rejected a private member’s bill which would have allowed “competent” adults with fewer than six months to live to seek professional help to kill themselves. Yet the issue has not gone away. Last November the supreme court dismissed an emergency application to hear a right-to-die case challenging the legal ban on assisted dying, but said that the matter was of “transcendent public importance”. On Thursday parliamentarians have a chance to restart that conversation with a Commons debate.

Not only is public opinion moving ahead of the law in the UK, but parts of Europe and the United States have shown that it is possible to regulate rather than prohibit. A humane option in this regard is needed as the nation’s population of older adults is growing. There are important considerations about how, if the law was changed, vulnerable people could be insulated from insidious pressures and how trust in the medical profession could be maintained. Lawmakers are the right people to find the balance between personal autonomy and how paternalistic the state should be towards its citizens in this regard. A law that is near-impossible to implement, ethically and practically, ought to be looked at again by MPs.