Whenever I hear or read the phrase "loved one", I shudder. Perhaps it comes of having read, at an impressionable age, Evelyn Waugh's satirical novel The Loved One. On a visit to the west coast of America, Waugh had been both repelled and fascinated by the Los Angeles necropolis known as Forest Lawn. It re-emerged in his novel as Whispering Glades; its faintly sinister staff would always talk about "your loved one", when dealing with enquiries from the public. The unvisited mausoleums of Whispering Glades contained nothing but "loved ones".

As usual, America's glutinous social euphemisms have, after a period of resistance, penetrated our own discourse. "Loved one" is now the accepted, indeed compulsory, description of any relative who has encountered – or is soon about to encounter – the funeral director's embalming fluid. Thus in his article in yesterday's Independent Anthony Lester introduced his advocacy of a measure which would legalise the export of Britons to a Swiss "assisted suicide" centre, by referring to them all as "loved ones".

As Lord Lester of Herne Hill, he is one of the most influential supporters of an amendment in the name of Lord Falconer to the Coroners and Justice Bill, which is to be debated and voted on this evening. The Bill itself was designed by the Government to strengthen the protection of those vulnerable to a growing number of websites encouraging people to kill themselves. The advocates of "assisted suicide" – a formidable and highly articulate body of men – have tacked on to this attempt to tighten the 1961 Suicide Act a measure which seeks to loosen it. Still, having failed on a number of occasions to pass a law specifically designed for their purpose, it is not so surprising that they would attempt a more circuitous route to the same objective.

Charlie Falconer's amendment is not one which would legalise any form of euthanasia on British soil: it is solely designed to lift the risk of prosecution from those taking "loved ones" to a country which is prepared to finish off the lives of people from outside its own jurisdiction. In practice this means only one thing: the so-called "clinic" known as Dignitas, which is in fact an apartment on the outskirts of Zurich belonging to a Mr Ludwig Minelli.

Falconer's amendment purports to be very tightly drawn up – as one would hope from a former Lord Chancellor. It requires two doctors to be "of the opinion in good faith" that the person is terminally ill and has the "capacity to make a declaration". In fact it is not made clear what "capacity" actually means; as for the two doctors, I'm not sure how rigorous a safeguard this is, given that the late Dr Harold Shipman never seemed to have any trouble getting a second doctor to sign cremation certificates. Similarly, Falconer's amendment makes no requirement that the doctors acting "in good faith" should have any knowledge of the "patient", or indeed ever met him or her, or even seen any case notes.

Above all, there are no visible safeguards against coercion or abuse by others which could have been subtly applied at an earlier stage, and would be extremely difficult to detect for a doctor with no prior knowledge of the family. Since the overwhelming majority of British doctors are opposed to handing out what amounts to pre-fabricated death certificates, in practice the doctors signing such certificates "in good faith" (to use Falconer's lawyerly phrase) would be among the relatively much smaller number who are genuine enthusiasts for a measure of euthanasia.

In his Independent article Lord Lester bases his case on the proposition that "modern medicine has created difficult ethical problems about how to balance the right to life and the patient's right to choose to accept or refuse medical treatment when life has become unbearable and death is imminent...not everyone wants doctors and nurses to strive to keep them alive."

If Anthony Lester tried this as an argument in a court of law he would be given very short shrift by any judge not actually fast asleep. It is already the case that patients can refuse medical treatment; indeed it is actually against the law for a doctor to insist on invasive treatment which the patient regards as unacceptable - this, for example, is why Jehovah's Witnesses are able to refuse any blood transfusions. Furthermore, when death is "imminent" (to use Lord Lester's word) it is absolutely standard for doctors to prescribe very powerful painkillers, such as Diamorphine, which can also suppress respiration.

There is, however, a vast ethical difference between treating severe pain with an indicated drug which can also have the effect of speeding up the process of dying, and injecting a patient with poison with the sole intent of ending his life immediately. Lord Lester may think that the latter is a form of "treatment", but that is only because he also seems to believe that dying is a form of therapy.

That is certainly the view of Ludwig Minelli, who told a House of Lords select committee on this matter that suicide is "a marvellous possibility." Yet this is not perhaps the best time for the Upper House to become so intimately identified with the proprietor of Dignitas. Last month the chairman of the Royal College of General Practitioners expressed himself "horrified" by the discovery that many of the 114 British "clients" of Dignitas had not been suffering from terminal illnesses at all.

More to the point, Mr Minelli is now being investigated by the Swiss authorities following statements made by Soraya Wernli, who, as a supporter of assisted suicide, had been a director of Dignitas. Ms Wernli, a former nurse, claims that Dignitas is "a production line of death concerned only with profits...[Minelli] was not interested in clients' diagnosis, just their money". She also described how she was asked to sort through plastic bin-liners full of mobile phones, spare change, and other personal effects of the deceased: "Minelli sold everything on to pawn and second hand shops."

Doubtless Lords Falconer and Lester would describe all this as irrelevant and say that Minelli is supplying a public need. They add that it is "agonising" for Britons to take their "loved ones" to Dignitas, without knowing whether or not they will be prosecuted on their return and that this uncertainty must be ended.

In practice, none of those people have been charged by the office of the Director of Public Prosecutions, which has concluded in every case that a prosecution "would not be in the public interest". This is presumably because those 114 cases (out of a total number of British deaths in the same period of about 6 million) were of the sort in which the compassion of the accompanying relative would have been overwhelmingly obvious to any jury.

How many much less compassionately conceived plans for 'assisted suicide' will have been deterred by the law as it stands, however? As one of the many concerned critics of Lord Falconer's amendment puts it, "Anyone who has worked with frail or elderly or sick people or with recently disabled or depressed people; anyone who has seen the darker side of some family dynamics knows also how dangerous any pro-euthanasia legislation would be."

Seen in this, the harsh light of real human desires, the question is not just about how to look after the best interests of so-called "loved ones" but also how to protect those vulnerable people for whom this phrase is a mask for something much, much darker.