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Court to the rescue? High Court refuses to restrict disclosure following a mistake

In the recent case of Pickett v Balkind, the court refused to grant an injunction to restrain the defendant from using a letter which was mistakenly disclosed in unredacted form and which subsequently called into question an expert’s independence.


The underlying dispute was a tree root subsidence claim relating to a residential property. The parties had each been given permission to adduce expert evidence from both a structural engineer and an arboriculturist.

In May 2022, the claimant’s solicitors informed the defendant’s solicitors that one of their experts, Mr Cutting, could not give evidence during the trial window as he would be recovering from surgery. The defendant’s solicitors were sent a draft application for an adjournment, supported by a draft witness statement which referred to a letter from Mr Cutting to the claimant’s solicitors and attached an unredacted version of that letter. This was subsequently filed with the court.

Whilst the letter detailed the upcoming surgery, it also referred to “suggestions/requests” made by counsel on the draft joint statement and it attached a revised draft for comment. The defendant’s solicitors wrote to the claimant’s solicitors to express concern that Mr Cutting appeared to have breached the Technology and Construction Court Guide (TCC Guide) in involving legal advisors in the drafting of the joint statement. In response, the claimant’s solicitor asserted that the material in the letter was privileged and the fact it was included in full in the exhibit was an obvious mistake. A new application was filed in which the letter was neither referenced nor exhibited.

An injunction was sought to prevent the defendant from using the draft witness statement originally sent to it. The claimant’s solicitors asserted that Mr Cutting’s comments in the letter related to an aide memoire provided by the solicitors to assist with the expert’s joint statement in the proceedings.

The defendant issued a cross-application seeking production of the “aide memoire” provided to Mr Cutting and permission to cross-examine him at trial on the preparation of the joint statement. Further, they sought permission to use the letter at trial and sought a copy of an earlier expert report by Mr Cuttings’ firm which had not been disclosed but was referred to in the report of the claimant’s arboriculturist.


HHJ Paul Matthews, sitting as a High Court judge, accepted he was bound by the principles established by Al Fayed v Commissioner of Police of the Metropolis (which allows for the possibility of an injunction in cases of obvious mistake) but acknowledged it was not to be construed as statute. The fact that the disclosure had not been made under CPR 31, but rather in support of an adjournment application, did not undermine the applicability of Al Fayed, despite the Al Fayed principles being concerned primarily with documents which had been made available for inspection as part of the disclosure regime.

Applying Al Fayed, the starting point was that, once a document had been shown to the other side, it was too late to claim privilege in order to attempt to correct the mistake by obtaining injunctive relief.

Thereafter, the judge considered that whilst the court had the power to prevent the use of documents “where justice requires”, this did not mean a “free-for-all, untrammelled by principle” and the decision would depend on all of the circumstances.

HHJ Matthews concluded here that the error was not “obvious” such that a reasonable solicitor would have realised it had been an error. A mistake by the claimant’s solicitor was not the only possible explanation and they may have thought that it did not matter whether privilege was waived, or that the letter would have more weight unredacted. Further, the defendant’s solicitor had relied on the unredacted letter to pursue a concern that the TCC Guide had been breached, which the judge regarded as “entirely legitimate and proper”.  As such, the judge:

  • Refused to grant an injunction restraining the defendant from using the letter at trial (including that Mr Cutting could be cross examined on the letter and the surrounding circumstances at trial);
  • Ordered the claimant to produce an earlier report of its arboriculturist which was subsequently referred to in the expert’s joint statement (on the basis that it was not privileged from production and should be disclosed under CPR Rule 31.13(2)); but
  • Refused to order production of the “aide memoire” provided to Mr Cutting on the basis that the judge could not be satisfied that it was part of the expert’s instructions and fell outside of the CPR 35.10 regime.


The decision serves as a warning about interactions between legal advisers and expert witnesses; the former should not be involved in drafting or negotiating the joint statement, nor suggesting amendments to the draft statement save in exceptional circumstances.

It is also a reminder of the risk of referring, in one expert report, to an earlier report if the instructing party does not wish to rely on the earlier report at trial.

Finally, the decision demonstrates a reluctance by the courts to restrict the use of material in litigation, even in cases where material was mistakenly disclosed. The fact that the material indicated a breach of the TCC Guide no doubt added weight to the argument here. Practitioners should take great care when disclosing documents, particularly at an interlocutory stage, and should not expect subsequent assertions of privilege to act as an automatic defence.

This article was first published on Practical Law Dispute Resolution blog 26th October 2022.

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