A conclusive grounds decision made by the Single Competent Authority appointed under the National Referral Mechanism Reform Programme was admissible as evidence in criminal proceedings in determining whether a defendant was a victim of criminal exploitation under the Modern Slavery Act 2015 Pt 5 s.45(4).
The Court held that expert evidence was admissible in criminal proceedings when the subject matter was something on which the ordinary person without particular experience in the relevant area could not form a sound judgment without the assistance of a witness with such experience. Factors relevant to trafficking or exploitation were not necessarily within the knowledge of the ordinary person.
Assessment of the significance of a given set of factors present in a particular case might properly be the subject of expert evidence.
A person with the necessary expertise could give context to the factors by reference to their wider experience, which might involve the expert giving evidence on one of the issues in the case.
The fact that the SCA decision-maker would not have prepared their minute of decision with a view to its being used as expert evidence did not of itself prevent its admission in criminal proceedings; nor would they have anticipated giving evidence in relation to their conclusive grounds decision, R. v GS  EWCA Crim 1824,  4 W.L.R. 167,  7 WLUK 736 considered (see paras 32, 45-46, 53 of judgment).