MA Psych Juris common mistakes
MA Psych Juris · Understand the traps and how to avoid them.
Applying the Dusky 'functional' standard as a checklist of factual knowledge, so the candidate concludes a defendant who can recite charges and courtroom roles is competent without evaluating whether they can actually assist counsel or make reasoned decisions.
Dusky v. United States (1960) is memorized as the two-prong 'factual and rational understanding plus ability to consult with counsel' phrase, and candidates treat each prong as a box to tick rather than a functional capacity judgment tied to the specific legal context. The word 'sufficient' in the standard invites a threshold mindset.
What to do instead
For every competency item, ask three separate questions: Does the defendant have factual understanding? Does that understanding have rational, reality-based quality (not just recitation)? Can the defendant apply it to their own case and to decisions with counsel? Write out how the specific legal demands (e.g., pleading, testifying, weighing a plea) interact with the defendant's deficits before choosing an answer.
Confusing the legal standards for competency to stand trial, competency to waive Miranda rights, competency to plead guilty, and competency to be executed, and importing the Dusky test into the wrong context.
All four use overlapping language ('knowing,' 'intelligent,' 'voluntary,' 'rational understanding'), and candidates assume one standard governs all. The distinctions are subtle: Miranda waiver focuses on the totality of circumstances and the suspect's understanding of the right and consequences of abandonment; guilty plea competency adds ability to understand the plea's consequences and assist in the plea decision; Ford v. Wainwright and Panetti v. Quarterman govern execution competency with a focus on rational understanding of the reason for punishment.
What to do instead
Build a one-page comparison grid with columns for the legal question, the governing case, the core capacity assessed, and who bears the burden. Rehearse the Panetti 'rational understanding of why' distinction versus mere factual awareness of the execution, and the Miranda totality-of-circumstances framing versus the Dusky functional test.
Treating the insanity defense and competency as interchangeable, or selecting an insanity answer when the question stem describes a present-ability issue (or vice versa).
Both involve mental disorder and both appear in criminal cases, and candidates conflate 'was the defendant able to know right from wrong at the time' with 'is the defendant able now to assist counsel.' The McNaughton, ALI/Model Penal Code, and Durham tests are memorized separately from competency doctrine, and the temporal focus (past at offense vs. present at trial) gets lost under time pressure.
What to do instead
Before answering, locate the timeline in the stem: offense-time cognition and volition point to insanity (McNaughton's cognitive prong, MPC's cognitive/volitional prongs, or Durham's product test depending on jurisdiction); present-time capacity points to competency. Note that a defendant can be incompetent and not insane, or insane and later competent; state that explicitly in your reasoning.
Interpreting base rates, sensitivity/specificity, and predictive values as if they were interchangeable, or assuming a high AUC means a test is accurate in a low-prevalence setting.
Forensic and psychology-law settings have low base rates for violence, malingering, and recidivism, and candidates learn instrument statistics as abstract psychometrics without connecting them to prevalence. Positive predictive value rises and falls with base rate, and candidates forget that a test with 90% sensitivity and 90% specificity can have a very low PPV when prevalence is 2%.
What to do instead
For any instrument item, write the 2x2 table with a plausible base rate before evaluating the claim. Compute PPV and NPV by hand once for a low-prevalence scenario and once for a high-prevalence one, and remember that likelihood ratios (not sensitivity alone) drive post-test probability. Check whether the stem's setting implies a low or high base rate before choosing.
Choosing a malingering or feigning measure based on its name or popularity without matching it to the referral question, the population, and the known limitations (e.g., using the Test of Memory Malingering as a stand-alone indicator of all feigning, or ignoring that symptom validity and performance validity are different constructs).
Candidates memorize instrument acronyms (TOMM, MMPI-2-RF validity scales, SIRS, M-FAST, Rey-15) as a list and assume any 'malingering test' answers any feigning question. They miss the distinction between performance validity (effort on cognitive tasks) and symptom validity (overreporting of psychiatric symptoms), and they overlook that feigning measures are not diagnostic of malingering by themselves.
What to do instead
Classify each instrument by construct (performance vs. symptom validity), by population (criminal forensic vs. civil disability), and by what it can and cannot establish. Remember that no single score diagnoses malingering; the standard requires converging evidence across multiple validity indicators plus collateral data, and that feigning measures cannot distinguish malingering from genuine disorder without that convergence.
Treating the MMPI-2-RF or MMPI-3 validity scales as direct proof of psychopathology or malingering without considering response-style confounds, and misreading clinical scale elevations as diagnostic.
Forensic assessment items reward knowledge of validity scale names (F, Fp, Fs, L, K, VRIN, TRIN), and candidates map an elevated F scale directly to 'malingering' or an elevated clinical scale to a diagnosis. They forget that F can reflect genuine severe distress, that Fp detects feigning in specific contexts, and that MMPI scales are not diagnostic categories.
What to do instead
For each validity scale, state what it actually detects and its known false-positive sources (e.g., F and Fp can elevate in genuine acute psychosis; L and K can reflect defensiveness or cultural factors). Practice interpreting a profile with a narrative that integrates validity, clinical, and collateral data, and never select a diagnosis from a single elevation.
Assuming that a psychological evaluation in a child custody or parenting capacity case should apply the same standard as an adult clinical evaluation, or offering a custody recommendation beyond the evaluator's role and data.
Candidates come from clinical training where the evaluator's job is to diagnose and treat; forensic child custody work requires answering the court's specific legal question (best interests of the child) with a multi-method, multi-source approach, and the evaluator must avoid dual roles and avoid advocating for a party. The 'best interests' standard is vague, and candidates fill the gap with clinical intuition.
What to do instead
Frame every child custody item around the legal standard and the evaluator's role limits: the evaluator assesses parenting capacities and the child's needs, uses collateral sources and observational data, avoids therapy-evaluation dual roles, and does not make the legal decision. Distinguish the evaluator's opinion from the court's determination and flag when data are insufficient to support a recommendation.
Conflating the roles of the treating clinician and the forensic evaluator, including assuming that a therapist's records or opinions can substitute for a forensic evaluation or that a treating clinician can serve as an expert witness on forensic questions without role clarification.
Candidates are trained in therapeutic roles and carry the assumption that more clinical contact means better forensic information. They miss that treating clinicians have a therapeutic alliance, may have been influenced by the patient, and did not use forensic methods; forensic ethics (e.g., Specialty Guidelines for Forensic Psychology) require role clarity and avoiding multiple relationships.
What to do instead
For role-conflict items, identify the primary client (court vs. patient), the purpose of the evaluation, and whether the clinician has a therapeutic relationship. State that a treating clinician can provide factual records and observations but should not opine on forensic ultimate issues without appropriate role clarification and methodology, and note the risk of dual-role bias.
Answering eyewitness identification and interrogation items from lay intuition rather than the research base, e.g., assuming confidence predicts accuracy, that lineups should be simultaneous, or that false confessions are rare and only occur with torture or severe coercion.
These are counterintuitive findings, and candidates default to common sense: confidence-accuracy correlation is weak, sequential blind lineups reduce false identifications, and false confessions occur in laboratory and real cases with compliant and internalized forms. Candidates also underweight situational risk factors (long interrogations, false evidence ploys, minimization) relative to dispositional ones.
What to do instead
Memorize the key experimental findings and their boundary conditions: estimator vs. system variables, the weak confidence-accuracy relationship and post-identification feedback effects, double-blind sequential lineup advantages, and the taxonomy of false confessions (voluntary, compliant, internalized). For interrogation items, separate situational risk factors from dispositional vulnerability and consider how the two interact.
Mixing up the legal standards and procedural rules in civil commitment, guardianship, and mental health law, such as applying the criminal 'beyond a reasonable doubt' standard to civil commitment or confusing the roles of the court, the treating facility, and the patient's rights.
Mental health law is a patchwork of constitutional minimums (Addington v. Texas requires clear and convincing evidence for civil commitment; O'Connor v. Donaldson requires dangerousness or inability to care for oneself), state statutes, and procedural protections. Candidates learn the cases as isolated facts and do not connect them into a procedural sequence, and they confuse voluntary admission, emergency detention, and involuntary commitment.
What to do instead
Build a procedural flowchart for civil commitment: emergency hold criteria and duration, probable cause hearing, standard of proof (clear and convincing under Addington), right to counsel, periodic review, and least restrictive alternative. Separately chart guardianship (decision-making capacity, court appointment) and confidentiality/privilege exceptions, and check which jurisdiction or rule the stem invokes.