Dr Graham Ellison of Queen’s University’s School of Law has warned against linking a reported rise in sex crimes to the explosion in readily available obscene material on the Internet.

Dr Ellison wrote to the Belfast Telegraph after PSNI Chief Constable George Hamilton sought to explain a 61 per cent rise in sex crime over the last six years by citing examples where extreme material had led to offending.

Dr Ellison said: “The assertion that watching such material (whether violent or not) is responsible for a quantitative increase in sexual offences is rather spurious, particularly since no sources were cited to substantiate the remark.”

He added: “However, there is now a huge volume of data from a range of clinical and social scientific studies to suggest that this material has either no effect on a person’s behaviour, or that its effects are inconclusive. Some studies actually suggest that exposure to it can even lead to a decrease in sexual offending. Just because ‘common sense’ tells us that something might be true does not actually mean that it is true.”

Dr Ellison pointed out that “better reporting, police recording etc” had contributed to the rise in figures but added: “The important point to emphasise is that it is notoriously difficult to read ‘increases’ in any crime based solely on police data.”