What is an expert witness's duty to the court?

In Plain English

An expert witness has a responsibility to help the court understand complicated subjects that they have special knowledge about. Their main duty is to the court, not to the person who hired them. This means they must be fair, honest, and unbiased in their opinions. They need to give their opinion in a timely manner, and consider all the facts, even those that might weaken their opinion. If they change their mind after writing their report, they have to let everyone know. Also, they should only give opinions on things they're actually experts in, and they need to be upfront if their report is based on incomplete or inaccurate information.

Detailed Explanation

Under the Federal Circuit and Family Court of Australia (Family Law) Rules 2021, Rule 7.18 outlines the duties of an expert witness to the court. These duties are paramount and supersede any obligation the expert may have to the party instructing or paying them.

Specifically, an expert witness must:

  • (Rule 7.18(1)) Assist the court with matters within their knowledge and capability.
  • (Rule 7.18(3)(a)) Provide an objective, unbiased, independent, and impartial opinion on matters within their expertise.
  • (Rule 7.18(3)(b)) Conduct their work in a timely manner.
  • (Rule 7.18(3)(c)) Avoid withholding agreement or avoiding agreement when attending a conference of experts based on instructions or requests.
  • (Rule 7.18(3)(d)) Consider all material facts, including those that may detract from their opinion.
  • (Rule 7.18(3)(e)) Inform the court if a question falls outside their expertise or if their report is based on incomplete or inaccurate information.
  • (Rule 7.18(3)(f)) Produce a written report that complies with rules 7.21 and 7.22 (not provided in the context).
  • (Rule 7.18(5)) Provide written notice if they change their opinion after preparing a report. If appointed by a party, notice goes to the instructing party; if appointed by the court, notice goes to the Registry Manager and each party.

The duty to the court arises when the expert receives instructions (under rule 7.13, not provided) or is informed they may be called to give evidence Federal Circuit and Family Court of Australia (Family Law) Rules 2021.