Inadvertent Waiver of Privilege

13/02/2026

By Philip Hughes

In the course of (or indeed prior to issue of) any Clinical Negligence claim, numerous documents will come into existence to which litigation privilege attaches. Without delving into the nuance of such privilege, it is described by the White Book as follows:

“Communications between a solicitor and a non-professional agent or a third party, directly, or through an agent that come into existence after litigation is contemplated or commenced and made with a view to such litigation, either for the purpose of obtaining or giving advice in regard to it, or of obtaining or collecting evidence to be used in it, or obtaining information which may lead to the obtaining of such evidence”[1].

Unfortunately, and despite best intentions, situations can arise where such documents and/or other privileged documents are inadvertently disclosed or are inadvertently mentioned in documents which are correctly and intentionally disclosed. Regardless as to whether any party is the discloser or the recipient, it is important to understand the implications of such inadvertence.

Disclosure of Entire Document(s)

The possibility that such a situation can arise is foreseen and dealt with by CPR 31.20:

“Where a party inadvertently allows a privileged document to be inspected, the party who has inspected the document may use it or its contents only with the permission of the court.”

This rule raises the obvious question: when will the court grant such permission?

The answer, in short, is that permission will be granted other than when it was obvious to the actual receiving solicitor or should have been obvious to the hypothetical reasonable receiving solicitor that the document was disclosed by mistake.

The fuller answer, as set out by Clarke LJ in Al-Fayed v Commissioner of Police of the Metropolis [2002] EWCA Civ 780, is that the following principles apply:

              “In our judgment the following principles can be derived…:

i)  A party giving inspection of documents must decide before doing so what privileged documents he wishes to allow the other party to see and what he does not.

ii)  Although the privilege is that of the client and not the solicitor, a party clothes his solicitor with ostensible authority (if not implied or express authority) to waive privilege in respect of relevant documents.

iii)  A solicitor considering documents made available by the other party to litigation owes no duty of care to that party and is in general entitled to assume that any privilege which might otherwise have been claimed for such documents has been waived.

iv)  In these circumstances, where a party has given inspection of documents, including privileged documents which he has allowed the other party to inspect by mistake, it will in general be too late for him to claim privilege in order to attempt to correct the mistake by obtaining injunctive relief.

v)  However, the court has jurisdiction to intervene to prevent the use of documents made available for inspection by mistake where justice requires, as for example in the case of inspection procured by fraud.

vi)  In the absence of fraud, all will depend upon the circumstances, but the court may grant an injunction if the documents have been made available for inspection as a result of an obvious mistake.

vii)  A mistake is likely to be held to be obvious and an injunction granted where the documents are received by a solicitor and:

• a)  the solicitor appreciates that a mistake has been made before making some use of the documents; or
• b)  it would be obvious to a reasonable solicitor in his position that a mistake has been made;

and, in either case, there are no other circumstances which would make it unjust or inequitable to grant relief.[2]

viii)  Where a solicitor gives detailed consideration to the question whether the documents have been made available for inspection by mistake and honestly concludes that they have not, that fact will be a relevant (and in many cases an important) pointer to the conclusion that itwould not be obvious to the reasonable solicitor that a mistake had been made, but is not conclusive; the decision remains a matter for the court.

ix)  In both the cases identified in vii) a) and b) above there are many circumstances in which it may nevertheless be held to be inequitable or unjust to grant relief, but all will depend upon the particular circumstances.

x)  Since the court is exercising an equitable jurisdiction, there are no rigid rules.”[3]

So, speaking practically, the best course of action for an inadvertent discloser would be to not disclose a legally privileged document.

The second-best course of action, and if the inadvertent disclosure can be identified in time, would be to flag to the receiving solicitor those documents which have been disclosed by mistake and before they have been inspected. Taking such action will place the receiving solicitor in knowledge that such documents have been mistakenly disclosed, and, by extension, it will then be very difficult for that receiving solicitor to argue that the mistaken disclosure was anything other than obvious to them.

If the second-best course of action cannot be taken by the disclosing party, then they are reliant on any disclosed documents being obviously legally privileged to the hypothetical reasonable solicitor. In the case of some documents (e.g., solicitor-client communications, advice from Counsel), this should be readily apparent. But, in the case of others (e.g., draft witness statements, expert reports which are not yet finalised), the situation may be irretrievable.

It is important to sound a word of caution to the receiving solicitor that they remain under a duty to act reasonably with regards obvious mistakes. Failure to do so is likely to result in an application for injunctive relief on the part of the disclosing party, with the recipient of the documents footing the costs of the same. Authority is very clear – in cases of obvious mistake, it should not be necessary for the court to intervene:

“55. Before parting with this case, I wish to add three general comments:

i)  In the electronic age, even with the help of sophisticated software, disclosure of documents can be a massive and expensive operation. Mistakes will occur from time to time.

ii)  When privileged documents are inadvertently disclosed (as is bound to happen occasionally), if the mistake is obvious, the lawyers on both sides should co-operate to put matters right as soon as possible.

iii)  The disclosure or discovery procedure in any common law jurisdiction depends upon the parties and their lawyers acting honestly, even when that is against a party’s interest. The duty of honesty rests upon the party inspecting documents as well as the party disclosing documents.

56.  It should not be necessary for either the parties or the courts to devote their resources to resolving disputes of this nature between solicitors.”[4]

Disclosure of Entire Document(s) – Iniquity

It is worth noting that there will be rare situations when the contents of a disclosed document are such that privilege will not attach to it even if it had been intended to.

Often described as being an ‘exception’ to legal professional privilege, iniquity provides that such privilege does not apply to documents which have come into existence as part of, or in furtherance of, a crime, fraud or other serious wrongdoing. The test for such iniquity paraphrased being whether, on balance of probabilities, the iniquity is more likely than not on the basis of the evidence available to the decision maker.[5]

However, it is important to draw distinction between documents where advice is sought regarding how to meet an allegation of e.g., fraud, and those created in furtherance of that fraud:

“To consult a solicitor about an intended course of action, in order to be advised whether it is legitimate or not, or to lay before a solicitor the facts relating to a charge of fraud, actually made or anticipated, and make a clean breast of it with the object of being advised about the best way in which to meet it, is a very different thing from consulting him in order to learn how to plan, execute or stifle an actual fraud.”[6]

So, if a document reveals a prima facie case of fundamental dishonesty (i.e., as opposed to a document asking how to respond to an allegation of fundamental dishonesty), then privilege will likely never haveattached to that document at all. And, although perhaps disclosed inadvertently, such a document should technically have been disclosed in any event because it was never privileged.

Parallels might be drawn between iniquity and the exception to the ‘without prejudice’ veil in circumstances where a ‘without prejudice’ document reveals unambiguous impropriety.[7]

Inadvertent Mention of Document

The situation with regards mention of a privileged document in a different and intentionally disclosed document is more nuanced. Whether privilege of the mentioned document has been inadvertently waived will depend upon:

• (a) Where the document is mentioned; and
• (b) Whether there is mere reference to the document or reliance upon the content of it.

The starting point is CPR 31.14:

“(1) A party may inspect a document mentioned in—

(a) a statement of case;

(b) a witness statement;

(c) a witness summary; or

(d) an affidavit

(e) [Revoked]

(2) Subject to rule 35.10(4), a party may apply for an order for inspection of any document mentioned in an expert’s report which has not already been disclosed in the proceedings.”

It is apparent that there is a distinction between expert reports on the one hand, and statements of case and witness evidence on the other.

Dealing first with statements of case and witness evidence, CPR 31.14(1) would seem to be prescriptive that any mention is sufficient to impliedly waive privilege, but this is not so:

“First, the mere fact that a document is ‘mentioned’ in one of the documents specified in CPR r.31.14(1) does not automatically and without more entitle the other party to inspect it. The Court retains a discretionary jurisdiction to refuse inspection”[8]  

Instead, there must be deployment of the contents of a privileged document within a statement of case or witness evidence. That is to say that the contents need to have been relied upon to some extent. Following a period of some uncertainty, it has now been seemingly conclusively resolved that it does not matter whether those contents are relied upon for the substantive claim or solely for an interlocutory purpose.[9]

Of course, what amounts to reliance or deployment remains a grey and contentious area. It is very likely to be the battleground for any contested application for disclosure.

Turning to consider mention of a privileged document in the report of an expert, the caveat for CPR 31.14(2) is that it is subject to CPR 35.10(4), but CPR 35.10(3) is also of relevance:

“(3) The expert’s report must state the substance of all material instructions, whether written or oral, on the basis of which the report was written.

(4) The instructions referred to in paragraph (3) shall not be privileged against disclosure but the court will not, in relation to those instructions—

• (a) order disclosure of any specific document; or
• (b) permit any questioning in court, other than by the party who instructed the expert,

unless it is satisfied that there are reasonable grounds to consider the statement of instructions given under paragraph (3) to be inaccurate or incomplete.”

Reconstituted into a more digestible form, a court will not order disclosure of the content of an expert’s instructions (or allow the same to be a topic for cross-examination) unless there are reasonable grounds to consider the statement of instructions in that expert’s report is either inaccurate or incomplete.

However, it necessarily follows from the above that any document which is not ‘instructions’, will be disclosable upon mention (i.e., deployment/reliance as described above). So, it is of some importance as to how ‘instructions’ are defined.

Fortunately for the instructing party, instructions in this context are given a particularly broad definition. Per Waller LJ in Lucas v Barking, Havering & Redbridge Hospitals NHS Trust [2003] EWCA Civ 102:

“Material supplied by the instructing party to the expert as the basis on which the expert is being asked to advise should in my view be considered as part of the instructions and thus subject to CPR 35.10(4).”

So, in Lucas, the Claimant was not required to disclose:

• (a) His draft witness statement which had been supplied to his medical expert, and where substantial parts of the same had been set out as part of the “material instructions” pursuant to CPR 35.10(3); and
• (b) A draft of a different expert’s report where a finalised version had subsequently been served.

Of course, the protection afforded to an instructing party by CPR 35.10(4) will not bite if their expert has set out an inaccurate or incomplete statement of instructions, or if there are reasonable grounds to consider the same. However, and again, interpretation favours the instructing party. And again, per Waller LJ in Lucas:

“The obligation under CPR 35.10(3) is to disclose the substance of all material instructions. The protection under CPR 35.10(4) relates to “any specific document” and “questioning in court” unless the statement of instructions given under paragraph (3) is inaccurate or incomplete. There is no requirement to set out all the information contained in the statement or all the material that has been supplied to an expert. The only obligation on the expert is to set out “material instructions”.” [Emphasis original]

So, what of mention in a document that is neither witness evidence nor an expert report? Well, the normal rules of disclosure would apply – i.e., if a document would fall within the scope of standard disclosure and privilege does not attach to it, it should be disclosed. But then, such a document would/should have been disclosed in any event.

Expert Shopping

Much has previously been written about expert shopping and Edwards-Tubb v JD Wetherspoon PLC [2011] EWCA Civ 136, and this is hardly surprising given it is now some 15 years old. But, it does warrant brief mention as being a circumstance where privilege, although not overridden, can be required to be waived.

Put succinctly, and slightly oversimplified, in circumstances where a party seeks permission for a new expert, permission for the same (if granted at all) would normally require waiver of privilege as to any existing expert’s report.

Summary

Perhaps the big takeaway from the above is that inadvertent disclosure or mention of any document is far from the end of the story. It is still very possible, and in the case of documents mentioned in expert reports perhaps even probable, that legal professional privilege will still apply. Regardless as to which side of the disclosure fence you reside, the initial inadvertence is the time to stop and pause for thought before expensive and unnecessary interlocutory proceedings ensue.

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[1] Para 31.3.8

[2] This would appear to be a direct reference to iniquity as an exception to privilege (see below), but potentially is cast wider.

[3] Para 16

[4] Atlantisrealm Ltd v Intelligent Land Investments (Renewable Energy) Ltd [2017] EWCA Civ 1029, per Jackson LJ

[5] For a fuller explanation of the principle of iniquity, see Al Sadeq v Dechert LLP [2024] EWCA Civ 28

[6] O’Rourke v Darbishire [1920] AC 581

[7] See, for example, Morris v Williams [2025] EWHC 218 (KB), where a ‘without prejudice’ communication offered an admission of fundamental dishonesty in respect of some elements of the Claimant’s claim as part of an offer of settlement.

[8] National Crime Agency v Abacha [2016] EWCA Civ 760, per Gross LJ

[9] Pickett v Balkind [2022] EWHC 2226 (TCC)