This is a link to a decision of the Court of Appeal in England, written by Sir Andrew McFarlane, President of the Family Division.
The important parts are as follows:
Paragraph 98, where the definition of an expert is a function of that person’s ability to help the fact-finder, based on that person’s knowledge, skill, expertise, training and education, on an issue requiring scientific, technical or other specialized knowledge. Where the person is not a member of a specific professional organization or regulated profession, this is not an automatic disqualification, but requires the court to take care to investigate whether it is appropriate to appoint such a person.
Paragraph 103, wher the court finds that PA is not a diagnosis or a syndrome, but is a matter of fact to be determined on the question whether there is behaviour which has an adverse impact on the relationship between the child and the parent.
‘3.8 Courts should expect that all psychologists based in the UK providing evidence in family proceedings are regulated by the HCPC (if they are practitioners) and/or that academic psychologists have Chartered membership with the BPS.
3.9 It remains at the discretion of the court to appoint individuals who are not eligible for Chartered membership of the BPS or qualified for registration with the HCPC but that the court determines have relevant psychological knowledge or training. However, it should be made clear in orders and letters of instruction that these individuals are not being appointed as psychologist experts but under the auspices of other professional frameworks, e.g. Independent Social Workers with additional psychological qualifications or Psychotherapists. These individuals are also distinct from psychologists in relation to their remuneration rates paid by the Legal Aid Agency.’