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InPsych 2015 | Vol 37

August | Issue 4

Cover feature : Assessment of capacity

Best practice in psychological assessment of capacity in legal settings

Tribunals, courts and other legal entities routinely seek expert psychological opinions to assist in determining whether or not an individual has the capacity to perform a legally-defined cognitive or behavioural function or set of related functions. Psychologists working in this area must understand the forensic context in which they are providing their assessment, have a keen awareness of the rights of the individuals whose capacity is in question, and meet the specific best-practice standards and procedural rules that pertain to evaluating the particular capacity.

The forensic context of capacity assessment

Provision of any psychological service within a legal setting is defined as forensic psychology, so psychologists providing assessments to assist legal entities to determine questions of capacity must therefore adhere to the general principles and ethical standards that underpin all forensic psychological practice (see Heilbrun et al., 2009; APS Guidelines for psychological practice in forensic contexts, 2013).

The psychologist’s expert opinions are provided to assist the tribunal in determining capacity, however, the final determination is the province of the tribunal and the psychologist should not suggest or assert a finding (unless the tribunal specifically asks for this). There are other particular requirements of the expert witness role and obligations within Australian jurisdictions (see Freckleton & Selby, 2009). Psychological assessments in this area of practice are investigative rather than therapeutic, so the psychologist needs to be skilled in investigative methods rather than the collaborative mindset that is more usual in therapeutic practice.

A central tenet is that the psychologist’s ultimate client is the tribunal, not the person whose capacity is being assessed. However, while psychologists providing capacity assessments are obliged to primarily assist the tribunal, they still have a broad ethical obligation to the individual being assessed. As with any area of forensic practice, dual roles such as being both a forensic evaluator and a treating clinician should be avoided, and where this is not possible supervision should be sought from an experienced forensic psychologist.

Resources that are critical reading for understanding the forensic context in this area of psychological practice can be found in the recommended reading list.

The rights of individuals whose capacity is being assessed

There are numerous pieces of legislation that define individuals’ rights that are often underpinned by Australia’s signature to United Nations conventions (e.g., Rights of the Child; Rights of Persons with Disabilities). While it is the role of the tribunal to balance the rights of the individual (e.g., the right to autonomy and self-determination) against other considerations (e.g., the need to be protected), psychologists should have at least a basic understanding of the relevant aspects of legislation and case law that guides decision-making in the relevant tribunal.

For example, the W.A. Guardianship and Administration Act (1990) states that “A guardianship or administration order shall not be made if the needs of the person … could … be met by other means less restrictive of the person’s freedom of decision and action” (s. 4), and “An order appointing a limited guardian or an administrator for a person shall be in terms that … impose the least restrictions possible in the circumstances on the person’s freedom of decision and action” (s. 6). The psychologist’s examination of the person for whom an order is sought should therefore be guided by an understanding of the need to consider less restrictive means and should provide expert opinions about feasible means (e.g., supported decision-making).

In some areas of capacity that fall within family law and child protection jurisdictions, the rights of the individual being assessed are not of primary concern and, rather, the rights and best interests of the child are paramount (see 60B and 60CC in Part VII of Family Law Act [1975]). For example, a psychologist’s assessment of an individual’s parenting capacity must focus on the best interests of the child and not on the rights of the parent (other than his or her general rights).

Best practice in assessment of capacity

A wide range of best practice principles apply to this area of forensic psychological practice and seven critical areas can be identified, which are summarised below.

Understand the legal context

Psychologists must have a good understanding of the legislation and common law pertaining to the specific legal questions that are being addressed in the assessment of capacity. Some legislation is very explicit in defining competence or diminished competence (e.g., the criteria for unfitness to stand trial are listed in the W.A. Criminal Law Mentally Impaired Accused Act [s.9]), while other legislation only more generally lists matters that must be considered by the professional undertaking the assessment of capacity.

Address relevant legal questions

The expert opinions formed by the psychologist undertaking the capacity assessment must be relevant to the specific legal questions before the tribunal. Those opinions must therefore pertain to relevant behaviours rather than to psychological

constructs or variables measured by a test. For example, when expressing opinions regarding decision-making capacities, it is not sufficient to outline the cognitive impairments identified by psychological tests. The psychologist must outline explicitly how those deficits will manifest in real-life contexts that are directly relevant to the legal capacity in question. The tribunal needs to know how likely it is that the individual will perform competently in a specific context, not simply that he or she is in the lowest percentile of the population on a particular sub-scale of a test.

While capacity is not an all-or-nothing thing, in many areas of law the tribunal must determine whether or not an individual has sufficient capacity. The tribunal determines where to draw a line in the sand, while the psychologist’s role is to provide adequate and relevant evidence to assist the tribunal to determine if the individual falls above or below the line that is drawn.

Focus on behaviour

Test and interview data should not be relied on solely as the basis of the capacity assessment. In order to provide a defensible basis for the opinions that the psychologist forms, behavioural measures and observations are almost always required as part of the capacity assessment. For example, in an examination of capacity of fitness to stand trial, it is not sufficient to show that standardised tests have identified areas of cognitive impairment. The psychologist must also demonstrate that the individual’s performance has been tested on analogous tasks to those that will be required during the specific type of trial the individual will face. Similarly, when assessing an individual’s parenting capacity, it is not possible for a psychologist to properly form opinions without direct behavioural examination of parenting behaviours. When evaluating an individual’s civil decision-making capacities, the process of obtaining and verifying informed consent for the examination provides useful behavioural data regarding the individual’s capacities (although is clearly not a sufficient test on its own).

Provide data with high probative value

The psychologist’s role is to be ‘helpful’ to the tribunal, so it is essential that the data that are provided are capable of proving relevant facts and can withstand the tribunal’s scrutiny. This requires comprehensive testing not only of the main hypotheses that arise from the psychologist’s review of documents and other background information, but that all plausible alternative hypotheses that can account for the initial data are properly investigated. This requires an iterative process of examination and re-examination.

With some tribunals, it is helpful not only to provide evidence about the person’s impairments, but also evidence of if and how those impairments can be managed or ameliorated. For example, courts are always keen to receive assistance in determining strategies that can be implemented during a trial that will improve an accused individual’s capacity to follow proceedings and instruct legal representatives. Similarly, tribunals that determine whether or not a guardian or administrator should be appointed are keen to receive evidence about how the individual can be supported in his or her decision-making.

Use multiple sources of data

It is critical to seek out and collect data from multiple sources. Each source of data will be limited by particular biases and reliability problems that need to be taken into account when analysing the full set of information uncovered during the examination. For example, in a guardianship and administration matter, different family members can provide relevant information, but each will be biased by his or her beliefs about the need for the individual to be protected, and possibly by other less altruistic motives. No source of data is free from bias and other reliability and validity problems, thus the importance of multiple sources of data.

Use forensically valid tests and assessment methods

Where possible, tests and other assessment devices that have been specifically validated for the particular forensic context should be used. If such instruments do not exist, then tests should be used that measure the relevant constructs and can withstand the tribunal’s scrutiny. For example, do not use tests that contain leading questions or items that may assist the individual to present a desired impression. Any relevant limitations of the tests used should always be noted in the report.

Be aware that capacity is not fixed

In many circumstances, an individual’s capacity changes across time. The psychologist’s assessment should also lead to opinions about the likely prognosis for capacity across time – for example, that capacity is likely to decline in a particular manner and timeframe, or capacity is likely to fluctuate according to particular circumstances or in response to particular factors.


It is essential that psychologists providing expert opinions to courts and other tribunals in the complex area of capacity assessment are able to integrate multiple sources of assessment information, have knowledge of legal processes and forensic psychology, are aware of individuals’ rights, and above all, exercise sound professional judgement. Armed with these skills, psychologists can provide vital expertise to assist tribunals to determine individuals’ capacities.

The author can be contacted at g.dear@ecu.edu.au


  • American Psychological Association. (2013). Specialty guidelines for forensic psychology. The American Psychologist, 68, 7-19.
  • Australian Psychological Society. (2013). Guidelines for psychological practice in forensic contexts. Melbourne: Author. Available at EG-Forensic.pdf
  • Freckleton, I. & Selby, H. (2009). Expert Evidence: Law, practice, procedure and advocacy (4th ed.). Melbourne: Lawbook Co
  • Greenberg, S. A. & Gould, J. W. (2001). The treating expert: A hybrid role with firm boundaries. Professional Psychology: Research and Practice, 32, 467-478.
  • Greenberg, S. A. & Shuman, D. W. (1997). Irreconcilable conflict between therapeutic and forensic roles. Professional Psychology: Research and Practice, 28, 50-57.
  • Grisso, T. (2010). Guidance for improving forensic reports: A review of common errors. Open Access Journal of Forensic Psychology, 2, 102-115.
  • Heilbrun, K., Grisso, T. & Goldstein, A. (2009). Best practices in forensic mental health assessment: Foundations of forensic mental health assessment. Cary, NC, USA: Oxford University Press.
  • Shuman, D. W. (1993). The use of empathy in forensic examinations. Ethics and Behavior, 3(3&4). 289-302.
  • Shuman, D. W., Greenberg, S., Heilbrun, K. & Foote, W. E. (1998). An immodest proposal: should treating mental health professionals be barred from testifying about their patients? Behavioural Sciences and the Law, 16, 509-523.

Disclaimer: Published in InPsych on August 2015. The APS aims to ensure that information published in InPsych is current and accurate at the time of publication. Changes after publication may affect the accuracy of this information. Readers are responsible for ascertaining the currency and completeness of information they rely on, which is particularly important for government initiatives, legislation or best-practice principles which are open to amendment. The information provided in InPsych does not replace obtaining appropriate professional and/or legal advice.