Practice Direction HC 142: generative AI in the High Court

Practice Direction HC 142, the Practice Direction on the Responsible Use of Generative Artificial Intelligence in Court Documents, came into force on 1 September 2026. It was published by Mr Justice David Barniville, President of the High Court. It applies to all proceedings currently before the High Court and to every court document prepared, produced or generated after that date.

The obligations do not sit with lawyers alone. HC 142 applies to any person responsible for a court document, which includes clients swearing affidavits, expert witnesses preparing reports, and litigants in person.

What HC 142 covers

The Practice Direction defines generative AI as technology or software capable of producing new content, including text, images, audio, video, data or computer code, usually in response to a user prompt.

Its purpose is to allow the responsible use of these tools while protecting the integrity of court proceedings. The High Court accepts that generative AI has a legitimate role. What it requires is that any content going before the court is current, complete, accurate and relevant, and that responsibility for it stays with the party filing it. Failure to comply may be treated as misleading the court.

What legal practitioners must do

The duties owed to the court as an officer of the court are unchanged. Use of generative AI must be assistive and never delegatory. Practitioners remain responsible for advising clients and expert witnesses of their own obligations of truthfulness and completeness in anything put before the court.

Practitioners should be particularly careful with material covered by a court order or by an express or implied undertaking restricting its use, disclosure or dissemination. HC 142 is clear that generative AI should not be used with such material, because doing so risks breaching the order or undertaking.

The new disclosure obligation

Much of what HC 142 sets out should already be standard practice. The genuinely new element is disclosure.

“Most practitioners already treat these tools as assistive rather than delegatory. What is new is that the use now has to be declared on the face of the document.”

The Practice Direction sets out declaration wording that must appear in one of the opening paragraphs of a witness statement or affidavit, and in an expert report. The appropriate text is at paragraphs 27 and 29 respectively.

Experts must be advised by the instructing practitioner to disclose the nature and extent of any generative AI use in drafting, analysing, interpreting or generating substantive content for their report. This allows the court and the other parties to assess the reliability, independence and evidential weight of the opinion.

“Experts are the immediate pressure point. A report that does not set out how these tools were used in its preparation invites a question about its weight, and that question is far better answered before it is asked.”

Litigants in person

HC 142 applies equally to litigants in person, who must manage their case in line with the Guidance for Non-Lawyers on the Responsible Use of Generative AI in Court Proceedings. The same sanctions apply for non-compliance.

What to do if you spot a problem

The Practice Direction expects parties to resolve issues between themselves rather than turning them into a tactical weapon. A party who identifies a potential problem should first raise it with the party responsible and allow a reasonable time for a response. That party is then responsible for bringing the matter to the attention of the court, explaining how it arose and how it was remedied. If they do not, the issue can be raised by the other party.

Sanctions for non-compliance

The penalties reflect the seriousness of the damage that inaccurate or fabricated material does to the administration of justice. Sanctions range from adverse costs orders to the strike out of a claim or defence, and extend to personal costs orders and sanctions against the legal practitioners involved.

What to do now

Anyone with proceedings before the High Court should check three things. First, whether any document already in preparation involves generative AI use that now requires disclosure. Second, that experts have been briefed on the disclosure obligation before they finalise their reports. Third, that internal practice on AI use with confidential or order bound material is understood by everyone touching the file.

HC 142 has immediate effect and will be felt across most High Court matters from the start of the new term.

Frequently asked questions

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When did Practice Direction HC 142 come into force?

It came into force on 1 September 2026. It applies to all proceedings currently before the High Court and to every court document prepared, produced or generated after that date.

Who does HC 142 apply to?

Any person responsible for a court document. That includes solicitors and barristers, clients swearing affidavits, expert witnesses preparing reports, and litigants in person.

Do affidavits and witness statements now require a declaration about AI use?

Yes. The Practice Direction sets out declaration wording that must appear in one of the opening paragraphs of a witness statement or affidavit. The appropriate text is at paragraph 27 of the Practice Direction.

Do expert reports require a declaration about AI use?

Yes. Declaration wording must also appear in an expert report, and the appropriate text is at paragraph 29 of the Practice Direction.

What do expert witnesses have to disclose?

The nature and extent of any generative AI use in drafting, analysing, interpreting or generating substantive content for their report. The instructing practitioner is responsible for advising them of this.

Can generative AI be used with documents covered by a court order or an undertaking?

No. HC 142 is clear that these tools should not be used with material subject to a court order or to an express or implied undertaking restricting its use, disclosure or dissemination, because doing so risks a breach.

What are the sanctions for non-compliance?

They range from adverse costs orders to the strike out of a claim or defence, and extend to personal costs orders and sanctions against the legal practitioners involved. Non-compliance may also be treated as misleading the court.

Colin Hayes, Partner
Áine Kelly, Senior Associate