Has Keir Starmer QC really made it possible for relatives to help loved ones to die without fear of prosecution, as the Times reported? Did the director of public prosecutions issue ‘tick-box guidelines’, as the Telegraph believed? And was there any justification for ‘deepening concerns’ reported in the Daily Mail that ‘a paid public official has, in effect, usurped the role of parliament by shaping the law on assisted dying’?

Much though it pains me to contradict my fellow journalists, I’m afraid the answer to all these questions is ‘no’.

But it’s not just the newspapers that seemed unable to understand the interim policy on assisted suicide issued by the Crown Prosecution Service last month. There seems to be a much wider incomprehension of how prosecutions are brought in England and Wales.

Let’s go back to first principles. It has never been the rule in this country that suspected criminal offences must automatically be the subject of prosecution. That was said by Sir Hartley Shawcross when he was attorney general in 1951. But the policy goes back much further. Ever since the office was established in 1880, the DPP has brought defendants before the courts only if he regards this as being ‘in the public interest’.

At first, that broad phrase was left undefined. But when the CPS was launched 23 years ago, it explained in some detail how it assessed the public interest. ‘Broadly speaking,’ the first code for crown prosecutors said, ‘the graver the offence, the less likelihood there will be that the public interest will allow of a disposal less than prosecution, for example a caution.’ The latest code puts it more bluntly: ‘public interest factors that can affect the decision to prosecute usually depend on the seriousness of the offence or the circumstances of the suspect.’

But Debbie Purdy persuaded the law lords in July that this code did not provide sufficient guidance for someone with a severe and incurable disability who was likely to need assistance in travelling to a country where assisted suicide was lawful. She wanted to know what factors the DPP was likely to take into account in deciding whether someone who assisted a person in her position would be prosecuted under the Suicide Act 1961.

Although Starmer did not want to publish a code dealing specifically with assisted suicide, the law lords required him to do so. The interim policy he published last month is already in force, though it may be amended in the light of public consultation before being finalised next spring.

As you would expect, the policy document lists a number of public-interest factors in favour of prosecution and a number against. Far from being ‘tick-box’ guidelines, some carry more weight than others. ‘Deciding on the public interest is not simply a matter of adding up the number of factors on each side and seeing which side has the greater number,’ the CPS says. ‘One factor alone may outweigh a number of other factors which tend in the opposite direction.’

For the Daily Mail, though, it’s all very simple: ‘The law as laid down by parliament spells out that it’s a criminal offence to "aid, abet, counsel or procure" somebody else’s suicide – and that anybody who does so can expect up to 14 years in prison. No ifs, no buts.’

But ‘ifs and buts’ are precisely what was intended. The Suicide Act 1961 goes on to say that nobody can be prosecuted for assisting in a suicide without the consent of the DPP. As Starmer explained last month, parliament would not have included that subsection if it had not wanted him to use his discretion.

Exercising their discretion is what previous DPPs did when considering eight cases of alleged assisted suicide abroad between 1998 and 2008; none led to a prosecution. It’s what prosecutors and police officers do every day of their working lives.

The Mail’s final argument is that only parliament can change the law of assisted suicide. Few newspapers seem to have noticed that parliament is doing just that: the Coroners and Justice Bill, likely to be passed next month, will amend the 1961 act by making it an offence to do an act capable of encouraging or assisting suicide, provided this was the defendant’s intention. It is fair to add, though, that the government does not intend this simplification to change the ‘scope’ of the current law.

But what of the broader argument that these guidelines amount to a change in the law and that any such change must be authorised by parliament? First, assisted suicide remains an offence and Starmer is giving no guarantees against prosecution.

Second, critics have to understand that primary legislation cannot cope with the subtle variables of human behaviour. Parliament could give its approval to Starmer’s code but it could never decide how to balance the various factors it sets out.

For example, should there be a prosecution for assisted suicide abroad if the person needing assistance had a ‘severe degenerative physical condition’ and had expressed a ‘clear, settled and informed wish to commit suicide’ but had done so at a time when his ‘capacity to reach an informed decision was adversely affected by a recognised mental illness’? How much weight should a prosecutor give to the assister’s membership of a group set up to provide ‘a physical environment’ for people to take their lives if this made it less likely they would ‘commit suicide in a public place’?

Fortunately, these are not the sort of decisions we journalists have to take.