Psychology and Law Foundations
This domain tests whether you can place psychological knowledge inside legal decision-making: who may testify, about what, and under which admissibility rule. Expect items contrasting adversarial and inquisitorial process, distinguishing clinical, actuarial and social-framework evidence, and asking which gatekeeping standard applies.
Admissibility standards
- US federal courts apply Daubert v Merrell Dow (1993): testability, known or potential error rate, peer review, and general acceptance, with Kumho Tire (1999) extending the inquiry to technical and specialised knowledge. Frye's general-acceptance test survives in some state courts.
- England and Wales applies R v Turner (1975) - expert evidence must be outside ordinary jury knowledge - with reliability scrutiny in R v Gilfoyle (2001) and duties codified in Criminal Practice Direction 19A.
- Australia applies R v Bonython (1984): the subject must be a field of specialised knowledge and the witness must be sufficiently qualified in it.
Roles and limits
Clinical opinion addresses the individual case; actuarial and social-framework evidence describes group base rates. Jurisdictions differ on ultimate-issue testimony: the Federal Rules permit it, English practice discourages experts from usurping the jury's function.
Worked example
A party offers a retired detective to opine that a suspect's account reveals 'staged' crime-scene behaviour. Under Daubert the claim states no testable hypothesis, cites no published error rate and has no peer review, so it fails relevance-reliability gatekeeping. A doctorate does not cure this, because expertise is topic-specific.
Traps
Confusing Frye with Daubert; assuming qualifications transfer across topics; presenting group base rates as though they diagnosed an individual; and opining on guilt rather than on psychological constructs.