A police chief would rather face the prospect of jail than obey a court order requiring his force to return computer hard drives to their owner. At issue is the big question of who ultimately makes the law in the UK: the police or the courts.

The story began in June last year when former computer forensics expert Jim Bates attended a police station in Bristol to clone computer hard drives alleged to contain paedophile material. These formed part of a case in an upcoming trial for making of indecent images, and despite Bates’ status as a now former expert – following a conviction for perjury in respect of his qualifications – it is claimed that the defendant had requested his involvement in the case on the basis of his in-depth expertise in these matters.

The police were unhappy with Bates' involvement: throughout the summer there was vigorous discussion of whether he should have been allowed access to the material in question and, according to Bates, pressure applied to him by the Crown Prosecution Service. This culminated, in September, in a police raid on his home which resulted in the seizure of 87 hard drives, and a reported 2,500 indecent images of children.

The police justification for this raid was that Bates had obtained the images through deception, and that the entire episode was part of a criminal conspiracy to obtain indecent images of children.

Earlier this month, a judicial review before the High Court upheld a complaint by Jim Bates that both the original raid, carried out to locate the cloned hard drives, and the extension of the search during that raid to encompass other materials on Bates' premises had been unlawful. The court ordered Avon and Somerset Police Force to return all materials that they had seized.

This weekend, it was reported that the chief constable of that force, Colin Port, would risk jail by refusing to comply with that order. Arguing that the ruling went against common sense, he said: "Clearly, defying the court is a serious matter and one that is not taken lightly.

"We don't know what's on these hard drives, but it is highly likely they contain indecent material going back to the 1990s. They were found with over 2,500 hard copies of child abuse images and they must have come from somewhere.

"Common sense dictates to me that we shouldn't be returning indecent images to anyone - yet I am prevented from even examining the material."

The legal issues in this case are complex, but boil down to the question of who determines expert status before the courts, and whether such a thing as "privileged status" for legal documents may be overturned by police.

In ordinary circumstances, where an individual is acting as an expert in order to testify before a court, they may have access to papers and other materials that are deemed to be "privileged". Such material may not be seized by police in the course of an ordinary search and should be returned at once if it is found that it has been taken.

The police felt that Bates’ conviction for perjury removed his status as an "expert" – and therefore also invalidated any claim to "privilege" in respect of material held at his property. The court ruled, however, that not even a court could overturn expert status: where an expert was discredited, that might go to the credibility of their evidence, but not to the status of the individual.

In addition, some of the material seized was likely to be privileged in respect of previous cases in which Bates had acted: the police should therefore not hold on to it.

Although the subject matter in question is highly emotive, the point at issue is legal dynamite. Within the UK legal system, various individuals and bodies, insofar as they are acting in a law enforcement capacity or as "officers of the court", may be allowed temporary exemption from laws applied to the general public. The police may break the speed limits where to do so is necessary in pursuit of offenders: the Sexual Offences Act 2003 made provision to allow individuals working for organisations such as the Internet Watch Foundation to access images that it would be illegal for the general public to possess.

According to Avon and Somerset Police, throughout this matter, their officers "believed that they were acting with good intent and in the interests of public safety and protection". Their Chief Constable has argued that this action is what the public would expect him to do.

Twenty-five years ago, a similar public interest defence was put before a jury in the case of a civil servant, Clive Ponting, accused of breaching the Official Secrets Act. The judge in that case directed that "the public interest is what the state says it is". The jury disagreed. ®