Protocol for Warning Letters


1. The Inquiry Rules 2006 (the Inquiry Rules) ensure that anyone who faces criticism is given a fair opportunity to respond to it. The process the Inquiry Rules prescribe, and which the Post Office Horizon IT Inquiry (the Inquiry) is adopting, to achieve this involves the sending of warning letters, although it is sometimes referred to as “Maxwellisation”[footnote 1].

2. Pursuant to Rule 13 of the Inquiry Rules, the Chair must not include any explicit or significant criticism of a person in an interim or final report unless the Chair has sent that person a warning letter and that person has been given a reasonable opportunity to respond to that letter (Rule 13(3)).

3. It is for the Chair to determine to whom warning letters should be sent. The Chair will be guided in such determinations by section 17(3) of the Inquiries Act 2005 (the 2005 Act), which provides that the Chair must act with fairness and with regard also to the need to avoid any unnecessary cost (whether to public funds or to witnesses or others) when making any decision as to the procedure or conduct of the Inquiry. 

4. The entitlement to warning letters contained in Rule 13(3) is not restricted to core participants or to those who have given oral or written evidence to the Inquiry.  

Contents of Warning Letters

5. In accordance with Rule 15 of the Inquiry Rules, warning letters must:

  a. state what the criticism or proposed criticism is;
  b. contain a statement of the facts that the Chair considers substantiate the criticism or proposed criticism; and
  c. refer to any evidence which supports those facts. 
6. The Chair may provide copies of the evidence referred to in the warning letter, if the Chair considers it appropriate to do so. 
7. The prescribed contents of warning letters, as set out in Rule 15 of the Inquiry Rules, are subject to any restriction on the disclosure of evidence, documents or information in accordance with sections 19 (restriction orders made by the Chair) and 23 (risk of damage to the economy) of the 2005 Act or resulting from a determination of public interest immunity. 

Arrangements for Sending Warning Letters

8. Where the intended recipient of a warning letter has designated an address for the purposes of Rule 3 of the Inquiry Rules (be it fax, postal or email), any warning letter will be sent to that designated address. 
9. Where the intended recipient has not designated such an address, the Inquiry team will take reasonable steps to contact that person to ascertain whether an address should be designated for this purpose. If any address is so designated, the warning letter and any associated documents will then be sent to that address. In the absence of a response from the intended recipient, the Inquiry will endeavour to deliver the warning letter in person in accordance with Rule 3(a). 

10. In accordance with Rule 13(2), the recipient of a warning letter may disclose it to their recognised legal representative. Where the recipient or intended recipient of a warning letter wishes to appoint a legal representative for designation as their recognised legal representative before the Inquiry under Rule 6 of the Inquiry Rules, they should notify the Solicitor to the Inquiry as soon as possible (see 'Contact us').
11. Where criticism or proposed criticism concerns a person who is deceased, the Inquiry will contact that person’s next of kin in order to give them an opportunity to make representations on behalf of that person. 


Applications for Funding for Legal Representation

12. In cases where a person may be subject to explicit or significant criticism during the Inquiry’s proceedings or in the report, or in any interim report, the Chair may make an award to that person in respect of legal representation at public expense (see paragraph 7 of the Inquiry’s Costs Protocol relating to legal representation at public expense (the Costs Protocol)). Where the recipient of a warning letter wishes to apply for funding for legal representation, an application should be made in accordance with paragraph 13 of the Costs Protocol. 
13. Pursuant to paragraph 8 of the Costs Protocol, awards will generally not be made for legal expenses of substantial bodies, or of individuals or organisations who could reasonably expect those expenses to be met by such bodies, or where there is an umbrella group which could adequately represent their interests, unless there are special circumstances which justify a call on public funds.


Duties of Confidence in Relation to Warning Letters 

General Position

14. As set out above, recipients of warning letters may disclose the contents of the letter to their recognised legal representative under Rule 13(2) of the Inquiry Rules. Pursuant to Rule 14(1), the contents of warning letters must be treated as confidential and this obligation is owed:
  a. separately by each member of the Inquiry team to the recipient of the warning letter; 
  b. by the recipient of the warning letter to the Chair; and
  c. by the recipient’s recognised legal representative to the Chair (where the recipient has disclosed the contents under Rule 13(2)). 

15. This obligation is owed in addition to any other obligations owed by those persons to the Inquiry (by way of confidentiality undertakings or similar).

Waiver of Confidentiality

16. The Chair, or the recipient of a warning letter, may waive the obligation of confidentiality in writing at any time under Rule 14(2) of the Inquiry Rules. The recipient of a warning letter who wishes to disclose its contents to any person other than their recognised legal representative should submit a written application to the Chair identifying any person to whom they wish to disclose the content of the warning letter and giving reasons. If minded to waive the obligation of confidentiality, the Chair may attach conditions and, in particular, may require any person in respect of whom permission to disclose is requested to give a written confidentiality undertaking before the disclosure is made. 
17. The Chair is prepared, without requiring individual applications under paragraph 16, above, to waive the obligation of confidence owed to him under Rule 14 to the extent required to enable the recipient of a warning letter to disclose its contents to:
  a. any professional body or defence union to which the recipient belongs; 
  b. the recipient’s employer or former employer; and
  c. any solicitor or counsel instructed by the recipient or by such a professional body, defence union, employer or former employer.
18. The general waiver granted by paragraph 17, above, is granted on the following conditions:
  a. the recipient of the warning letter notifies the Solicitor to the Inquiry of any person to whom they intend to disclose the contents of the warning letter under this waiver before the disclosure is made;
  b. any person to whom disclosure is made in terms of this waiver is subject to the same obligation of confidence owed to the Chair as the recipient of the warning letter; and
  c. the recipient makes any person to whom the contents of the warning letter are disclosed aware of that condition. 


Duration and Breach of Obligation of Confidence

19. Under Rule 14(3) of the Inquiry Rules, the obligation of confidence owed by the Chair to the recipient of the warning letter ends when the Chair’s report is signed in accordance with section 24(4) of the 2005 Act. All other obligations of confidence as set out in paragraph 14, above, end when the Chair’s report is published (Rule 14(4)). 
20. A breach of an obligation of confidence is actionable (that is, it may give rise to a civil claim) at the instigation of the person to whom the obligation is owed, subject to the defences to actions for breach of confidence. 

Response to Warning Letters 

21. The Inquiry recommends that, where the recipient of a warning letter (or their next of kin, as the case may be) wishes to respond, that response is provided in writing, in the form of a letter addressed to the Chair and delivered by email to the Solicitor to the Inquiry ( 
22. All warning letters will specify a date by which any responses should be returned, but the Inquiry asks that all responses be sent as soon as possible. Time limits for responding may vary depending on the nature and extent of the criticisms or proposed criticisms concerned. The Inquiry will consider an application for an extension of time if there is a good reason why a person will be unable to comply with the time limit. An application for an extension of time must be made in writing by e-mail to the Solicitor as soon as possible and, in any event, before the expiry of the period specified in the warning letter.
23. The Inquiry team will not enter into correspondence concerning the terms of, or amendments to, any criticism or proposed criticism.

24. The Chair will take account of any written statement made in response to a warning letter when finalising the report as regards the criticism or proposed criticism. Under Rule 16 of the Inquiry Rules, in determining the weight accorded to any evidence before the Inquiry, the Chair will disregard whether (or not) a warning letter was sent to any person. 


Issued under the authority of the Chair on 01 December 2021.


1.  This term originates from a case concerning Robert Maxwell (Maxwell v Dept of Trade and Industry [1974] QB 523) after which it became commonplace for public inquiries to give an opportunity to respond in advance to those whom they intended to criticise. This process is now codified, for the purpose of statutory inquiries, in the Inquiry Rules 2006 in Rules 13 to 15.