The new policy on assisted suicide is not the mercy killing charter that some religious groups, charities and newspapers have painted it.Director of public prosecutions Keir Starmer, announcing the new policy yesterday, made it clear that mercy killing remains a crime – the same as any other killing.

You’ll be in the dock on a murder charge if you give the mad aunt in the attic a lethal injection to put her out of her misery. Or starve someone who’s in a coma. Or smother a disabled baby.

That’s because you’ve killed someone. It’s not assisted suicide because, as Starmer said: ‘The act of suicide requires the victim to take his or her own life.’

The new policy arises from a Crown Prosecution Service consultation that received the remarkable total of more than 4,800 responses. Some 4,000 of those were from individual members of the public, which shows what a sensitive issue this is. And then there were responses from doctors, other healthcare professionals, representatives from several faiths, academics, lawyers, public servants and politicians, as well as over 100 organisations.

The resultant policy speaks a lot of common sense.

Killing is a crime, it says, and so under certain circumstances is assisted suicide. You can’t help someone to kill himself if he lacks the mental capacity to make an informed decision to commit suicide, for instance. You’ll be prosecuted. Similarly, you can’t help someone under 18 years of age – they are not considered mature enough to reach the decision.

There are 14 other, in Starmer’s words, ‘public interest factors’ in favour of prosecution. For example, you’ll be in the dock if you pressured someone to commit suicide or accepted payment to help someone kill himself. You’ll also be prosecuted if you were not ‘wholly motivated by compassion’ – because you stood to gain from the victim’s death. Doctors, nurses, carers, prison officers and others with professional obligations towards victims will also face prosecution.

There are just six ‘public interest factors’ against prosecution. Prominent among these is where the victim has reached a ‘voluntary, clear, settled and informed decision to commit suicide’. Your assistance under such circumstances won’t automatically lead to prosecution. This is clearly the case with Debbie Purdy, incidentally, who is entirely compos mentis and has made public her wish to die when her medical condition makes living unbearable.

Other factors against prosecution include cooperating with the police after the event and seeking to dissuade the victim from suicide.

There is one grey area, however. Suppose you help your spouse to kill himself or herself to escape the pain and indignity of a terminal illness. You’ve acted out of compassion, which is good, but you also stand to benefit from the victim’s death – because you will inherit the entire estate – which is bad.

Will you be prosecuted or not? Starmer has the answer: ‘Each case has to be considered on its own facts and merits.’