In Pyrrho Investments Limited and another v MWB Property Limited and others  EWHC 256 (Ch), the UK High Court considered whether to permit the use of predictive coding in an electronic disclosure exercise. This is the first reported English High Court decision on this issue (although predictive coding is well-established in the US and has previously been approved by the Irish High Court (Irish Bank Resolution Corporation Limited and others v Sean Quinn and others  IEHC 175)).
“Predictive coding” (also known as computer assisted review), works by analyzing the coding decisions made on a sample document population, and extrapolating those decisions across a wider population. The judge in this case advised that “best practice” would be for a single, senior lawyer, who has mastered the issues in the case, to then consider the initial representative sample (marking it as relevant or not), in order to “train” the software to review the whole document set. Further statistical sampling by humans (usually taking at least 3 rounds) is then conducted to ensure the quality of the exercise. Once an acceptable level of accuracy is reached, the software then categorizes all the documents. (See also the more detailed description of the process at paragraphs 19-24 of the judgment.)
This was a multi-million pound case with 3.1 million electronic documents to review. The parties had agreed on the use of predictive coding between themselves, subject to the court’s approval.
The judge referred to the references to automated electronic disclosure in Goodale v Ministry of Justice  EWHC B41 (QB). He also considered some of the US authorities and the Irish Bank case where the use of predictive coding had been contested (paragraphs 25-31, judgment). He approved the use of predictive coding because:
- Experience in other jurisdictions suggested that predictive coding is useful in appropriate cases. There was nothing to suggest it was less reliable than manual and keyword review (and it may be more reliable).
- It brings consistency, and could allow the electronic documents in this case to be reviewed at proportionate cost. A full manual review would be unreasonable.
- It was not contrary to the CPR (see PD 31B.25), the parties had agreed that it should be used and trial was some way off so there was scope to use other methods if need be.