Today's Times devotes a page to Elish Angiolini who is stepping down as Lord Advocate, Scotland. (No link as Times is behind a pay-barrier) The article detailed her idea that communications technology could corroborate a victim's account of a sex attack. She supported use of mobile phone company records and social networking sites and had seen a rise of securing convictions. Scots law requires corroboration of a witness's testimony and she had introduced this with expert opinion evidence from psychologists who examine mobile and Facebook records for clues as to a person's behaviour after being attacked. This can encourage victims to come forward where they might fear that they would be believed.
Of course,all this has attracted the criticism of the Human Rights Squad who describe the expert evidence as pseudo-science.
The old Judges Rules governed what police officers should do in the course of their investigations so as to show Judges that things were done fairly. The very first of these rules allowed the police to question any person with a view to finding out whether, or by whom, an offence had been committed. 'Question any person' gave approval to the use of experts and this should include psychologists.
Persons accused of a crime have many routes open to them to avoid questioning or to dispute such evidence. It is, of course, open to them to retain their own expert. These give the man in the dock an advantage over the forces of law and order. My contention, formed from having been an investigator, is that all relevant evidence should be put before a Judge and Jury. The Judge would decide whether it was relevant and the jury - possibly with guidance at summing-up time - would rule as to which side had made it's case. This should happen regardless of how the information was obtained (short of torture obviously). If the accused was shown to have used some form of trickery in the commission of the offence, why is it wrong to bar the police from using trickery in their investigations? We now have international courts of appeal so the idea that the law could ride rough shod over some harmless but unlucky defendant is obsolete.