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The English High Court has approved the use of predictive coding in an electronic disclosure exercise in a recent case [1].


Predictive coding is a type of search technology which uses a coded dataset to automatically identify relevant electronic documents to be disclosed.

Initially a sample of the documents (around 1600 to 1800 documents in this case) is reviewed by a senior solicitor who is familiar with the case. This sample is used to train the software as to which documents are relevant.

The software analyses documents and scores them for relevance to the issues in the case. A further series of batches of documents are then reviewed by the software and then reviewed manually by the solicitor.

Any errors are fed back into the system to reduce the margin of error. Once the margin of error is within agreed parameters, the remaining documents are run through the software and a list of the relevant documentation is produced.

Despite the up-front cost, the use of predictive coding should speed up the disclosure process, as opposed to manual review, which should in turn lead to reduced cost overall.

In this particular case [1] there were 3.1 million electronic documents to review and the parties asked the Court to approve the use of predictive coding in the electronic disclosure process.

The use of predictive coding was approved and in doing so, cases in other jurisdictions (most notably the US and Ireland) were referred to, which suggested that predictive coding is useful in appropriate cases. It also noted that:

  1. No evidence indicated that using the software led to less accurate disclosure being given.
  2. The fact that one senior solicitor would be setting the parameters for the software would mean the results were more consistent compared to a manual review, where it is likely the documents would be reviewed by several lower grade fee earners, each applying the criteria independently.
  3. Nothing in the CPR or Practice Directions prohibited the use of such software.
  4. The number of electronic documents to be considered in the case was huge and the cost of manually searching them would be enormous and therefore unreasonable.
  5. The estimates given in the case for the cost of using predictive coding were far less expensive than for a full manual review.
  6. The estimated costs of using the software were proportionate to the value of the claim.
  7. There would be plenty of time before trial to consider other disclosure methods if the predictive coding route turned out to be unsatisfactory.
  8. The parties had agreed on the use of the software and how to use it.

So, what does this mean?

Although each case will turn on its individual facts, and the use of predictive coding will clearly not be appropriate in every case, this case provides a useful summary of the factors to be taken into account when deciding whether the use of predictive coding software would be suitable in any electronic disclosure exercise.

This post was edited by Lisa Smith. For more information, email blogs@gateleyplc.com.

[1] Pyrrho Investments Ltd v. MWB Property Ltd

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This blog is intended only as a synopsis of certain recent developments. If any matter referred to in this blog is sought to be relied upon, further advice should be obtained.