The perpetrators of sex crimes are notoriously difficult to bring to justice, but can more be done to prevent them offending in the first place?

The answer is yes, in the view of Police Scotland, which is why it is testing an innovative scheme to warn off suspected sex attackers with no previous convictions. The pilot scheme will involve having two officers visit the homes of "persons of interest", men who have come to their attention for targeting vulnerable women for sex, where they will be issued with formal letters warning them that they are being closely watched.

The singling out of people who have no previous convictions on suspicion of their future intentions naturally raises civil liberties concerns. Is there a danger that innocent men could be targeted? The way this scheme has been conceived, however, provides a degree of confidence.

Officers will only approach individuals about whom they have had complaints and information from several different sources, giving police cause to believe they pose a serious risk to women. They will almost certainly have been interviewed under caution on previous occasions in connection with sexual offences. Unfounded accusations of sexual assault or rape are sometimes made against innocent men but police will be looking for a pattern of behaviour.

The hope is that having the police bear down on these persistent predators will give them a jolt, causing them to change their behaviour. It is not realistic to imagine that any police warning will deter the most cynical of attackers but it is likely that it will scare off others and spare some women the trauma of abuse.

The danger that an innocent man could be branded a sex offender in his own community as a result of being targeted in this way is reduced by the fact that information on the men concerned will not be shared by police with any third parties, including the suspect's partner and family, though obviously the sight of officers on his doorstep may occasion some speculation by neighbours.

The scheme is another sign of Police Scotland's ongoing commitment to tackle sexual crime. The rape conviction rate in Scotland has long been a cause of despair among police and campaigners. As Detective Superintendent Louise Raphael makes clear, officers are not prepared to sit by powerlessly and do nothing in those cases where there is not enough evidence to take a case of suspected sexual offending to court.They want to prevent such crimes from occurring in the first place. Reducing this type of offending behaviour, which by its nature takes place behind closed doors, requires innovative thinking by the police and this is another welcome sign that officers are determined to meet that challenge.

Police Scotland are sensible to start with a pilot scheme in one area and assess how it works from that, particularly in relation to ensuring suspects' human rights are not violated. However, this initiative clearly has the potential to prevent rapes and sexual assaults, and deserves to be given a chance.