Very often, in disputes involving technical aspects, expert evidence can make or break a case. Here is a list of six things to remember when engaging and working with an expert:

1. Make sure your expert is independent

To reduce the risk that your expert might be accused of lacking independence, you should select an expert who has no connection to the instructing party. Although an expert who has previously acted as a consulting expert to a party is not disqualified from acting as an expert witness later on, consider the weight that the arbitrator will place on his/her evidence.

2. Engage your expert as early as possible

It is extremely important to retain your expert as soon as possible for several reasons: a) your expert can advise you at every step of the case and his/her opinion at an early stage will help determine your strategy throughout the proceedings – early assessment of a case will also mean you are better placed to make a sensible calderbank offer to the other side to protect yourself on costs (see our Guidance Note on calderbank offers here); b) the earlier you engage your expert, the longer he/she will have to prepare; c) if you engage your expert early, you avoid the risk that he/she will have already advised the other side and thus be conflicted out of acting for you.  

3. Check your expert’s qualifications and make sure he/she is technically excellent with practical experience

Your expert should be specifically qualified in the topic he/she will be giving evidence on. You should review the qualifications, education and experience of a potential expert to ensure he/she is able to give convincing opinions on the specific issues in your case. It is also worth checking that he/she has not previously written anything which conflicts with your position.

4. Ensure your expert is articulate, available and approachable

Find an expert who is articulate and able to convey his/her views both orally and in writing. Your expert should (both in the report and in oral evidence) be able to phrase complicated issues in simple, clear language.

Make sure your expert is available to dedicate the necessary time to read into the case and prepare for the hearing.

5. Brief your expert fully

You should provide your expert with detailed written instructions and make sure he/she has access to all the relevant documents. It is important not to withhold any material or relevant information from your expert, even that which is unfavourable to your case. This is so your expert can advise fully and there is no risk that your expert will change his/her mind when presented with the full facts later down the line.

Your expert should be present to hear the evidence of the other witnesses at the hearing so that he/she can address and comment on any issues discussed.

6. Protect communications with your expert  

Once legal proceedings have been reasonably contemplated by the parties, communications between parties and their experts should be covered by legal professional privilege. However, the scope of such privilege varies between jurisdictions. You should mark all communications with your expert as confidential and privileged.

There is always a risk that you might have to disclose the written instructions provided to your expert and so you should avoid making comments on the merits of the case or your strategy in those instructions.