We decided to outsource the review of around two million electronic documents, within two months, for a major High Court dispute. The electronic documents to be reviewed were uploaded to a document review platform hosted in the UK. A legal process outsourcer (LPO), based in India, then accessed and reviewed the documents via a secure internet connection. The LPO team, comprising 110 Indian lawyers, undertook the vast majority of the review work. A review team based in the UK undertook sample checking of the LPO team's work.

Training the local reviewers to the level required to complete a review is perhaps the most significant challenge. While most overseas LPOs have experience of US disclosure, far fewer have experience of applying the English disclosure test (the disclosure test). The disclosure test requires a reviewer to understand, in some detail, the pleaded case. Consequently, the members of the LPO team may initially be uncomfortable with the scope of the test and be tempted to try and oversimplify it.

While conference calls and video-conferencing provide part of the solution, these are less successful for complex matters that involve large teams. Cultural differences, and a natural deference to the instructing firm, can mean that reviewers may be slow to ask questions. In particular, it is almost impossible to gauge the comprehension of reviewers when they are listening in silence to a training call.

For these reasons (if local laws allow), there is no substitute for a representative of the instructing firm travelling to the LPO and training the review team in person. In our experience, talking reviewers through "live" documents face to face proved to be the most effective way of getting them actively to engage in how they should classify documents. A related issue is whether anyone from the instructing firm (or junior counsel) should supervise the review at the LPO site (see box "Embedding a supervisor").

Illness and other absenteeism (due, for example, to extreme weather and transport problems) can be unpredictable and potentially high. To provide cover, the instructing firm should train a larger number of reviewers than will initially be employed on the review.

There are many ways in which a review process can be structured. Many LPOs recommend 100% quality control, at least during the early stages of a review. Under this model, another member of the LPO team will consider every document a second time. As the team's comprehension and confidence grows, it is possible to reduce the percentage of documents subject to this control. As with all changes made to the process over time, the instructing firm should record these changes so it can explain them to the court later as necessary.

Whether or not a supervisor from the instructing firm is embedded in the offshore LPO team, accurate and timely feedback from the firm's case team on individual documents is essential. We successfully ran a feedback log that listed all queries and documents identified by the LPO team. Here, time differences can be an advantage. The LPO can send queries at the end of the offshore working day that the instructing firm can answer before the next offshore working day begins. In the early days, our feedback log was supplemented with a daily update conference call to discuss both general progress and learning points arising out of the queries that were raised.

At least until offshore document review becomes more commonplace, it is likely that the instructing firm will also wish to undertake quality control by sampling. This would typically include sampling of documents already dismissed as not relevant by the LPO team.

Another practical consideration is to ensure that IT support for the review platform is available throughout the offshore working day. Failure to provide this support could lead to reviewers sitting idle in front of a crashed system while they wait for the UK working day to begin.

One real risk of using an offshore review is the lack of flexibility as a deadline approaches. New tranches of documents will inevitably emerge as the review process proceeds. The traditional approach used by UK or US firms where junior lawyers and paralegals are called on to work late into the night might not be available.

While LPOs are used to employing large teams to review a fixed-size set of documents, they have less experience of managing a growing document set to meet a fixed deadline. In India, this situation is compounded by the fact that many LPOs run minibuses to transport their staff between home and work, which limits the length of the working day. Also, unexpected closures for public and religious holidays can erode time left for completing a review.

Again, having a supervisor embedded in the offshore review team can aid the LPO in understanding the need to meet these deadlines and helping it to find imaginative solutions to do so.

One key question is how the quality of an offshore document review compares with a London-based review. Our experience, based on a series of parallel tests, was that the quality of the review was broadly comparable to a review by a team of London paralegals. In India, working at a LPO for Western clients is regarded as a good role for law graduates who may have no other route into a restricted profession. Thus, our team was eager to learn and committed to working on document reviews.

Unsurprisingly, we found that many of the challenges of running such a review sprang from the loss of the ability to walk down the corridor and informally direct the review team. The upshot is that offshore reviews, although powerful and cost-effective, require a level of planning and process management rarely seen in conventional reviews.