Joan Smith: Tony Nicklinson's legacy: his case will save lives

When Tony Nicklinson died on Wednesday, there was widespread sympathy for a man who had been paralysed from the neck down. The previous week he had wept in front of TV cameras, devastated by the High Court's refusal to give him an assurance that anyone who helped him to die would not face a charge of murder. Photographs of Mr Nicklinson before his illness, looking healthy and tanned, offered a painful contrast with the helplessness he endured after a massive stroke in 2005. The case has redoubled calls for a change in the law on assisted dying.

Few people could witness Mr Nicklinson's plight and not be moved. But I was troubled by the images of his distress that circulated widely after he lost his case, and not just because they felt like an intrusion into private grief. There's a clear danger that ethical issues will get lost in this focus on a handful of tragic individuals; it's also worth noting that doctors, who would be called on actively to end lives if the law were to be changed, oppose a change in the law. Two months ago, at the BMA's annual conference, doctors reiterated their opposition to assisted dying.

They have good reasons. There is a huge difference between withdrawing medical treatment in terminal cases and actively helping someone to die, especially when the patient – as in many of these cases – is not actually dying. It's clear from the debate at the conference that many doctors don't want to be put in a position where they would be asked to kill people.

I'm sure Mr Nicklinson's family had his best interests at heart. But the debate about assisted dying is weirdly dissociated from the real world, in which relatives and carers often abuse elderly and disabled people. The frequency of domestic violence – and, more recently, "honour"-based violence – shows that the family is far from being the safe place campaigners imagine it to be. Husbands kill their wives, parents murder their children, and some relatives pressure the elderly into handing over money or changing their wills. Some families are loving but many are not, and even well-intentioned spouses and adult children get worn down by caring for a relative with huge physical and emotional needs.

People with debilitating but not immediately fatal conditions already have to deal with discomfort and loss. I'm not sure how doctors are supposed to differentiate between someone who genuinely wants to die and a situation in which they've been made to feel a burden on their family. Even "living wills" don't provide a definitive answer, because someone may feel very differently once a hypothetical fear becomes reality.

Lifting protection from millions of vulnerable people because of a small number of tragic cases is a drastic response. It also ignores the sound principle that extreme cases make bad law. It's perfectly possible for someone to be distressed and wrong, a fact that's been overlooked in the emotive discussion of the Nicklinson case.;