Part 25 Expert Evidence: When the Court Allows an Expert

Part of: Your First Family Court Hearing

Part 25 expert evidence is evidence from a psychologist, doctor, valuer or other specialist that the family court has allowed under Part 25 of the Family Procedure Rules 2010. Nobody can put expert evidence before a family judge without permission. In a children case, you also need permission before you instruct the expert or have a child assessed. The judge agrees only if the evidence is necessary, and the rules set a deadline for asking.

This guide explains the necessity test and how to make a Part 25 application. It also sets out what changes between children and money cases, and how to question a report you disagree with. It forms part of our guide to your first family court hearing and covers the law in England and Wales.

Want an expert in your case, or worried about one the other side wants? You can book a free initial consultation for initial advice from one of our specialists before your next hearing.

What is Part 25 expert evidence?

It is opinion evidence from someone with specialist knowledge, put before the court with the judge’s permission under Part 25 of the Family Procedure Rules. Common examples include a psychological assessment of a parent, a hair strand drug test, a medical opinion on an injury and a valuation of a home, business or pension.

Some evidence that looks expert does not count. Section 13 of the Children and Families Act 2014 excludes evidence from local authority staff working on their own council’s case. It also excludes a Cafcass or Cafcass Cymru officer acting in that role (s.13(8)). So a council’s social work assessment and a Cafcass report need no Part 25 permission. For the same reason, the judge will ask why they cannot answer your question before agreeing to bring in someone new.

What does the expert owe the court?

Their duty is to help the court on matters within their expertise. That duty overrides any obligation to the person who instructs or pays them (FPR r.25.3). The report must explain the facts and research behind each opinion, and it must summarise any range of opinion on a question (PD25B para 9.1). At the end, the expert must confirm that they understand that duty and have complied with it (r.25.14(2)).

What makes Part 25 expert evidence necessary?

In a children case, the court can give permission only if the evidence is necessary to assist it to resolve the proceedings justly (s.13(6)). A report that would simply be useful does not meet that test.

The judge must also weigh a list of factors (s.13(7)). They include the likely impact on the child’s welfare and the questions the expert would answer. The judge considers what other expert evidence already exists and whether someone else could give the same evidence. Finally, the judge looks at the effect on the timetable and the cost.

Money cases and other non-children cases use a slightly different test. There, the evidence must be necessary to assist the court to resolve the proceedings (r.25.4(3)). In deciding, the judge weighs the issues, the questions and the effect on the timetable. Any missed deadline counts, and so does the cost (r.25.5(2)). Our guides to the independent social worker and the forensic accountant in divorce show how the test works for two common kinds of expert.

How do the rules differ in children and money cases?

The biggest difference is when you need permission. In a children case you need it before you instruct anyone, while in a money case you need it only before the report reaches the judge (PD25D para 2.1).

Children cases cover more than disputes about where a child lives. A claim for money for a child under Schedule 1 to the Children Act 1989 also counts as children proceedings for Part 25 (PD25C para 1.2). In a children case, a report obtained without permission is inadmissible unless the court rules otherwise. The same applies to a child examined or assessed without permission (s.13(2) and (4)).

How do you make a Part 25 application?

You apply in the existing case, as early as you can, using the court’s Part 18 application procedure (r.25.7(1)). In a children case that usually means form C2, and in a money case after divorce form D11. Either way, attach a draft of the order you want (r.25.7(2)(b)).

The application must name the field of expertise and, where practicable, the expert. It must also set out the issues the evidence covers and say whether a single joint expert could give it (r.25.7(2)). In a children case, you must list the questions the expert will answer as well (r.25.7(3)). Our C2 application guide explains the form itself.

What else must a Part 25 application in a children case show?

Practice Direction 25C adds a longer list (para 3.10). It asks for the expert’s CV and whether they are a regulated expert. It also asks for their availability, the timetable for the report, the likely cost and how the fee will be split. Most importantly, you must explain why Cafcass, the local authority or an expert already in the case cannot properly give this evidence. Answer that point directly, because the judge has to consider whether someone else could give the evidence (s.13(7)(e)).

Does the expert have to be regulated?

In a children case issued on or after 20 July 2026, usually yes. The court may give permission for Part 25 expert evidence only if it comes from a regulated expert (FPR r.25.5A). That means someone regulated by a UK statutory body, on a register accredited by the Professional Standards Authority for Health and Social Care, or regulated under the Legal Services Act 2007 (r.25.2).

The rule does not cover an international social worker, a technical expert or an expert in a Schedule 1 claim (r.25.5A(2)). Technical experts give evidence on digital forensics, DNA, handwriting or toxicology.

A judge can still allow an unregulated expert when no regulated one is available. That is the case when only an unregulated expert can resolve the issue, or when instructing a regulated one would cause significant delay that is not in the child’s best interests. The judge must then give reasons (r.25.5A(3) to (5)). Cases issued before 20 July 2026 keep the old rules (Family Procedure (Amendment) Rules 2026, rule 6).

Can you speak to an expert before permission?

Yes, within limits. Children proceedings are confidential, but you may make preliminary enquiries of a proposed expert. You can share enough about the case for them to decide whether they can take it on (PD25C paras 3.3 and 3.4). The expert should then confirm that the work is within their expertise, that they can meet the timetable and what they will charge (para 3.5). Where the regulated-expert rule applies, also ask for confirmation and evidence of their regulated status.

Plan your Part 25 expert evidence request

Most requests turn on the kind of case you are in, who or what the expert would assess, and how far the case has gone. Choose your answers to see the permission you need, your deadline and what the judge will want to see. Nothing you choose leaves this page.

One shared expert, or one each?

The rules prefer a single joint expert, instructed by all the parties, wherever possible (PD25C para 2.1). Where two or more parties want expert evidence on the same issue, the court can direct that one expert gives it (r.25.11(1)).

The process starts with a list. The party who wants an expert sends the others one or more suitable names. In a children case, the others then have 5 business days to object and suggest alternatives (PD25C para 2.2). In a money case they have 10 business days (PD25D para 2.2). If you still cannot agree, the court can choose from the names you put forward (r.25.11(2)).

A single joint expert works from one jointly agreed letter of instruction, unless the court directs otherwise (r.25.12(1)). The parties are also jointly and severally liable for the fees unless the court directs otherwise (r.25.12(6)). In practice, the expert can look to either of you for the whole bill. However, the court can cap the fees before the expert is instructed (r.25.12(5)).

What happens once the judge gives permission?

Permission covers only the expert or field named in the application, and the order sets a date for the written report (r.25.8(1)). In a children case, the judge also approves the questions and fixes the date the expert must receive the letter of instruction (r.25.8(2)).

One party takes responsibility for that letter. It sets out the context, the questions the court approved and the documents the expert will read (PD25C para 4.1). The instructions are not privileged, so the other side can see them (r.25.14(3)).

The expert gives evidence in a written report unless the court directs otherwise (r.25.9(1)). The court will direct an expert to attend a hearing only if that is necessary in the interests of justice (r.25.9(2)). If an assessment of a parent is part of the plan, our guide to the parenting assessment explains what that process involves.

How can you challenge Part 25 expert evidence?

Start with written questions to the expert. You can put them once, within 10 days of the report being served, to clarify the report, and you must copy them to every other party (r.25.10(2)).

The answers become part of the report (r.25.10(3)). If an expert instructed by another party does not answer, the court can stop that party relying on the evidence. It can also stop them recovering the expert's fees from anyone else (r.25.10(4)).

Where experts disagree, the court can direct them to discuss the issues. They then prepare a statement of what they agree on and where they differ, with reasons (r.25.16). Once a party discloses a report, any party may use it at a hearing (r.25.15). A second report of your own is no shortcut in a children case. Without permission it is inadmissible unless the court rules otherwise (s.13(2)). Our guide to non-accidental injury covers disputes about medical experts in more detail.

Part 25 expert evidence: frequently asked questions

General information about the law in England and Wales, not advice on your circumstances.