Expert witness duties for psychologists in Australian courts

Psychologists and neuropsychologists are often asked to give opinion evidence in courts and tribunals. When they do, they take on expert witness duties that come before any loyalty to the party paying them.

This guide is for lawyers instructing psychologists, and for psychologists new to legal work. It summarises the main codes of conduct in Australian courts, what they require in a report, the professional obligations psychologists carry, and practical tips for instructing an expert.

Why expert witness duties matter

Courts rely on experts to explain matters outside ordinary knowledge, such as the effects of a brain injury or a person’s decision-making capacity. That only works if the expert is independent.

The Federal Court’s Expert Evidence Practice Note (GPN-EXPT) puts it plainly. Its Harmonised Expert Witness Code of Conduct states that an expert witness is not an advocate for a party and has a paramount duty to assist the Court impartially. State codes say much the same.

What can go wrong

When an expert’s evidence looks partisan, poorly reasoned or outside their expertise, a court may give it little weight or refuse to admit it. That can harm the client’s case and increase costs. For psychologists, conduct in legal work is also subject to professional standards, and concerns can be raised with the regulator.

Most problems are avoidable. They usually come from unclear instructions, missing records, or a report that states conclusions without showing how they were reached.

Which code applies

The code depends on the court or tribunal. Common examples include:

Other states, territories and tribunals have their own rules. Always check which rules apply and give the expert a copy.

एन.एस.डब्ल्यू.

The Land and Environment Court of NSW explains that under Schedule 7, an expert’s report and oral evidence cannot be admitted unless the expert has acknowledged reading the code and agreeing to be bound by it. The expert’s overriding duty is to assist the court impartially.

विक्टोरिया

Victoria’s Form 44A states that an expert has an overriding duty to assist the Court impartially on matters relevant to their area of expertise. In criminal trials, the Supreme Court reissued Practice Note SC CR 3 on 1 June 2025.

Family law

Part 7.1 of the Federal Circuit and Family Court of Australia (Family Law) Rules 2021 deals with experts. It includes rules on single expert witnesses, the expert witness’s duty to the court (rule 7.18) and the contents of an expert’s report (rule 7.22).

In practice, this means a single expert is often used in family law. The parties can appoint one jointly, or the court can order that a single expert be appointed. Psychologists preparing parenting or family assessments should be familiar with these rules. Our article on parenting capacity assessments explains more.

What the codes require in a report

The details vary, but the codes share common requirements. A report should usually include:

• the expert’s name, qualifications and relevant experience
• an acknowledgement that the expert has read and agrees to be bound by the code
• the facts and assumptions each opinion is based on
• the reasons for each opinion
• any literature or other materials relied on
• the examinations and tests used, and who carried them out
• a declaration that the expert has made all the inquiries they believe are desirable
• any qualifications, and whether an opinion is incomplete because of insufficient information
• a summary, if the report is long or complex.

Experts should stay within their area of expertise and say so when a question falls outside it.

Other duties that often arise

Conferences and joint reports

Experts may be asked to meet and prepare a joint report. The NSW code expects experts to work cooperatively, exercise independent judgement and try to reach agreement, and not to act on an instruction to withhold or avoid agreement.

Concurrent evidence

Some courts hear experts together, sometimes called “hot tubbing”. The Federal Court practice note describes this as a way to help the judge compare competing opinions.

Changes of opinion

If an expert’s opinion changes in a material way, they must say so promptly, usually in a supplementary report.

फीस

The NSW code requires disclosure of contingent fee or deferred payment arrangements. Payment should never depend on the opinion given.

Professional obligations for psychologists

Court codes sit alongside professional standards. The Psychology Board of Australia’s Code of conduct for psychologists took effect on 1 December 2025. According to the Board, it replaced the APS Code of Ethics as the foundation for professional expectations.

Several sections are directly relevant to expert work:

• Section 8.8 covers legal, insurance and other assessments. Psychologists must clarify their role, explain the purpose, nature and extent of the assessment, and obtain the person’s explicit consent.
• Section 3.2 requires psychologists to explain their role, the likely uses of information and the limits to confidentiality.
• Section 8.12 deals with recognising and managing conflicts of interest.
• Section 1.1 requires psychologists to work within the boundaries of their competence.
• Section 8.3 requires psychologists to protect the integrity of assessment methods, which includes test security.

Treating psychologists as experts

A treating psychologist knows the client well, but their therapeutic role can make impartiality harder. Section 4.9 of the Code addresses multiple relationships that might compromise objectivity. If a treating psychologist is asked to give expert opinion, the relationship should be disclosed, and an independent expert may be more appropriate for contested issues.

Tips for lawyers instructing a psychologist

• Send a clear letter of instruction with the specific questions and the relevant legal tests.
• Attach the applicable code and ask the expert to acknowledge it in the report.
• Provide all relevant material, including documents that may not help your client. The Federal Court practice note expects this.
• Do not pressure the expert toward a particular view.
• Allow enough time for records review, assessment and report writing.
• Check that the expert’s qualifications match the questions.
• Keep communications with the expert in writing where possible, as they may be disclosed.

Invictus Health कैसे मदद कर सकता है

Our psychologists and neuropsychologists prepare medico-legal assessments in line with the applicable expert codes. We also provide capacity assessments और neuropsychology assessments. Neuropsychology reports are reviewed by Dr Judy Tang OAM.

कृपया संपर्क करें to discuss a referral. This article is general information and is not legal advice.