When Family Court Documents Are Needed in a Criminal Trial

In family law proceedings, documents filed by each party are generally protected from being used outside the case. This protection, known as the Harman undertaking, aims to preserve confidentiality and prevent misuse of sensitive evidence.

But what happens when one party faces serious criminal charges—and believes those family law documents might help them defend themselves?

That’s exactly what happened in Simon & Birch [2025]. Mr Simon, the applicant, asked the Family Court to release documents from earlier property proceedings so he could use them in his upcoming District Court criminal trial.

This blog explains what the Court decided, why it granted the release, and what this means for others in similar situations.

Background of the Case

• • Mr Simon and Ms Birch were previously in a relationship and had been involved in family law proceedings over property settlement.

• • In 2023, their dispute ended with final consent orders in the Family Court.

• • However, Mr Simon was later charged with serious criminal offences allegedly involving their children.

• • His criminal trial was due to begin in 2025 in the South Australian District Court.

• • Mr Simon asked the Family Court to let him use certain documents and affidavits from the past family law proceedings to assist in his criminal defence.

What Is the Harman Undertaking?

The Harman undertaking is a legal obligation that prevents parties from using documents disclosed in one court case in another case without permission.

It’s designed to:

• • Protect privacy and confidentiality

• • Encourage honest disclosure in family law

• • Prevent documents from being misused in unrelated proceedings

Unless a judge specifically allows it, you can’t reuse affidavits, expert reports, or case files from family law in other legal contexts—even if those documents contain relevant or exculpatory information.

What Did Mr Simon Want?

Mr Simon applied to be released from this legal obligation so he could use:

• • Multiple affidavits filed by Ms Birch

• • Evidence from third-party witnesses

• • Case outlines and court orders from their earlier case

He argued that these documents:

• • Might contain contradictions or inconsistencies helpful to his defence

• • Could assist in cross-examining Ms Birch in the criminal trial

• • Were directly connected to the issues he was being prosecuted for

His lawyer said that if convicted, Mr Simon faced a long prison sentence, so using these documents was essential to a fair trial.

What Did Ms Birch Say?

Ms Birch opposed the application, arguing that:

• • Mr Simon hadn’t shown any valid reason to access the documents

• • The request was too broad and should be narrowed

• • Many of the documents—especially from her father and another third party—were irrelevant because those people wouldn’t even be testifying in the criminal trial

She offered a compromise: if the Court was going to release documents, it should only include specific paragraphs from specific affidavits—not the full documents.

What the Law Says

The Court relied on a range of previous cases and legal principles:

1. 1. Implied Undertaking Is Binding
      The Harman rule applies unless a court formally grants leave. This protects privacy and integrity in family law.

1. 1. Special Circumstances Can Justify Release
      The Family Court can release documents if there are special circumstances, such as:
      

       

      • • A criminal trial
      • • Overlapping facts between cases
      • • A serious risk to a party’s liberty or legal outcome

1. 1. Discretion Is Broad
      Courts don’t need “extraordinary” reasons. If there’s a good reason to allow the documents to be used, and it helps achieve justice, that can be enough.

What the Court Decided

Judge Dickson found in favour of Mr Simon.

The Court Ordered:

• • Release of the listed documents from the earlier family law case

• • Permission to use those documents only for the upcoming criminal trial

• • The release applied to both Mr Simon and Ms Birch, ensuring fairness

The Court did not limit the release to only select paragraphs, as requested by Ms Birch. It held that:

• • It was not the Family Court’s role to decide which parts were useful or admissible in the criminal case

• • That was a matter for the criminal trial judge

Key Reasons for the Decision

• • Seriousness of the Charges
    Mr Simon was facing significant criminal allegations with possible imprisonment. That created a compelling reason to access documents that might assist his defence.

• • Link Between the Cases
    The family law and criminal matters involved overlapping events and facts—making the documents potentially relevant.

• • Right to a Fair Trial
    Cross-examining Ms Birch on prior statements in her affidavits could be crucial for Mr Simon’s defence, especially on issues of credibility.

• • Efficiency and Justice
    The Court declined to limit which parts of the affidavits could be used. It trusted the District Court to manage issues of relevance or admissibility.
    
    

What About Legal Costs?

Both parties had asked for legal costs to be awarded in their favour. But the Court decided each party should:

• • Bear their own costs

• • Avoid further financial disputes over a case already emotionally and financially taxing

The Court noted that Mr Simon’s request had evolved over time, making it harder for Ms Birch to respond clearly. It also noted that even if both parties had agreed, the Court still had to determine if special circumstances existed.

What Can We Learn?

This case is a good reminder of how family law procedures interact with criminal law—and how courts prioritise justice even when it means crossing typical boundaries.

Key takeaways:

You can’t reuse family court documents elsewhere without permission.

But you can ask the Court to release them—especially for criminal defence.

Courts look at fairness, overlap, and the risk to personal liberty.

If allowed, the release is strictly limited to the new legal matter—such as a specific trial.

Full disclosure doesn’t always mean full access—you need to justify why it’s necessary.