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Whose DNA profiles should police be allowed to keep in their databases? The only fair and effective answer is everybody’s.

DNA profiling is a powerful forensic technique. It has led to the conviction of many criminals who would otherwise have eluded justice, and the freeing of many innocent people who had been wrongly convicted.

Its success in solving crimes depends on finding a match to a DNA profile generated from tissue fragments left at a crime scene, so many countries have set up databases of their citizens’ DNA profiles, and often retain the original samples too. The UK’s database includes the profiles of 7.5 per cent of its population, the highest proportion in the world. Even so, a match can be found for only around half the usable tissue samples taken from crime scenes.

This is the case even though the UK database contains the profiles not only of convicted criminals but also of people who have been arrested, regardless of whether they were then charged with an offence, let alone convicted. Civil liberties advocates say that including the profiles of innocent people is unjust – and the European Court of Human Rights recently agreed. Yet removing these profiles will mean that fewer crimes will be solved.

Many other countries are wrestling with this issue. One possible answer – not yet adopted anywhere in the world – is to record everybody’s profiles at birth or on entry to the country. A universal DNA database of this kind would not solve all crimes: in many cases, no DNA sample is available, or would be irrelevant because the alleged perpetrator’s identity is not in question. But it would ensure a match could be found for most crime-scene DNA samples, while also ensuring people arrested but not convicted are treated no differently to the rest of the population. There is no other way to achieve this.

There are privacy issues, especially if tissue samples are retained in addition to the profiles derived from them. While profiles alone can reveal little about people besides their parentage, frozen samples allow future sequencing of the genome, which will reveal ever more about us. But the risks have to kept in perspective: if someone wants to find out your genetic secrets, there are many other ways to do it.

Read more: Blueprint for a better world