Where corroborating evidence is available to support allegations of family violence, it should be placed before the Court. The Federal Circuit and Family Court of Australia (Family Law) Rules 2021 (Cth) permit the tendering of such material through affidavit evidence and supporting documents.
However, it is equally important to recognise the limits of lay evidence and to understand when expert evidence is required to prove particular allegations or consequences of family violence.
The Limits of Lay Evidence
As a general principle, witnesses may give evidence only of facts within their own knowledge. Under the Evidence Act 1995 (Cth), opinion evidence is generally inadmissible unless it falls within a recognised exception.
Sections 76 and 79 of the Act reflect this distinction. Section 76 excludes opinion evidence, while section 79 permits opinion evidence where it is based on specialised knowledge derived from training, study or experience.
As a result, parties and lay witnesses cannot give evidence about matters of medical science, diagnosis or causation. Where such matters are relied upon, expert evidence will usually be required.
When Expert Evidence Becomes Necessary
Expert evidence may be required where a party seeks findings that go beyond observable behaviour and into matters requiring specialised knowledge.
This commonly arises in parenting proceedings where a party contends that family violence has resulted in a diagnosable mental health condition such as post-traumatic stress disorder, and that this condition affects parenting capacity or the ability to safely manage time arrangements.
In Keane & Keane, the Court emphasised that findings about mental illness and its impact on parenting cannot be made on the basis of lay evidence alone. Medical or psychological expert opinion is required where such findings are central to the relief sought.
Expert Evidence in Property and Future Needs Claims
Expert evidence may also be required in property settlement matters where a party seeks a future needs adjustment on the basis that family violence has reduced their earning capacity.
In Pantoja & Pantoja, the Full Court confirmed that allegations of reduced earning capacity due to psychological injury caused by domestic violence must be supported by appropriate expert evidence. Lay assertions are generally insufficient.
This may include medical evidence addressing diagnosis and causation, psychological or psychiatric reports, and vocational or functional capacity assessments.
Strategic Considerations
Understanding when expert evidence is required is critical. Failing to adduce expert evidence where it is necessary may result in findings not being made, limited weight being given to alleged impacts, or adverse outcomes in parenting or property matters.
At the same time, expert evidence should be used proportionately. Not every allegation of family violence requires expert input. The key question is whether the Court is being asked to make findings that depend on specialised knowledge rather than ordinary human experience.
What to do to Get Help
If you are experiencing domestic or family violence, confidential support is available through 1800RESPECT. If you are in immediate danger, call 000.
Where family violence is relevant to parenting or property proceedings, early legal advice can assist in identifying whether expert evidence may be required and how it should be obtained.
At Powell Family Law, strategy meetings are available to assess evidentiary needs, including whether expert evidence may be necessary, and to develop a careful, proportionate approach to progressing your matter.
This Article Forms Part of a Series
This article forms part of our Proving Family Violence in Family Law Cases series, which explores how family violence — including coercive control — is defined, identified, evidenced, and assessed by Australian family law courts.
