Commissioning a report from a third party expert on one of the issues the Expert Witness has been instructed to consider

Question: 

Is it acceptable for an Expert Witness to commission a report from a third party expert on one of the issues the Expert Witness has been instructed on and then use the third party expert opinion in their report?

Answer:

If there is a particular aspect of a matter which is outside your own expertise but needs to be addressed, particularly if it needs to be addressed before you can form a proper view on the matters within your expertise, you should flag this to the instructing solicitor and get them to procure a report from the other expert or to instruct you jointly.  You should contact them to explain what is needed and why. At the same time, you could suggest an expert who could provide that expertise; however, it is for the Instructing Party to make the appointment. If that opinion is crucial to your own opinion, you should then wait to see what the solicitors state before preparing their draft report on inadequate evidence.

Don’t forget that in court proceedings (and sometimes also in arbitration) the instructions to the expert must be disclosed to the opposing party. There is no orderly way of achieving this if the expert goes off on their own to instruct another expert.

Where an addition report is being relied on, you could consider appending the other experts report to yours and explain within your report that you are relying on xx report in relation to a specific area.

This does not apply, of course, to the commonplace situation in which the expert gets a team acting under their supervision to undertake tests or carry out research. In that scenario the position should be spelled out in the report and in an ideal world the members of the team identified somewhere, even in an annexe.