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The Role of Expert Testimony in Court

Posted: 04-Jun-2015 16:58:00
Author: Chris Raske


The work of the expert witness is pretty well entrenched within the legal industry, so there is an extensive degree of overlap between the two fields.

Expert and legal professionals both:

  • Offer specialist insight into issues that their clients don't fully understand;
  • Attend mediations and court proceedings in order to resolve disputes;
  • Owe a special duty of care to third parties.


Experts are likely to have different opinions from lawyers because they have different goals.

Experts :

  • Are reliant on technical data relating to matter of fact; and
  • Ultimately owe a duty to court.

Whereas lawyers:

  • Are reliant on principles relating to matters of law; and
  • Ultimately owe a duty of care to their client.

This begs the question....

Where does each opinion stand in the eyes of the court?

This is obviously dependant on the case in question. If the key question is, say, "did the defendant copy source code?"  then it is likely that alot of emphasis will be placed on the expert's opinion.

Experts need to be careful in these situations, because it may well be the case that the expert is the only person who really understands a given subject. This gives their opinions a significant amount of weight, so they must be careful not to become pseudo-advocates.

A case study

IT Group's Tony Sykes has recently been involved in a case centering on phone hacking (found here), which serves as decent example of weight being placed on both the technical and legal aspects. To quickly sum up, the claimant (Voiceflex) provided the defendant (Frip) with an internet telephone system which was hacked to the extent that over 10,000 calls were made over a 38hr period. The issue was whether the defendant (Frip) was liable to pay for the calls.

Expert evidence

Expert evidence played a key role in the first point, which was essentially that Frip had not taken reasonable steps to prevent unauthorised access to the system, and was therefore in breach of contract. Alot of attention was given to expert analysis here, because it was largely dependant on whether or not an 8-digit numerical password was strong under these circumstances. The judge ultimately found that it was, which caused Voiceflex's claim for breach of contract to fail.

From here....

The case was largely based around legal aspects.  It shifted from a claim of damages to one for the price of the calls on the basis that Voiceflex "supplied a service to Frip, which was 'always on'". This involved a legal analysis of the terms and specific wording of the contract which ultimately circumvented the previous expert analysis, (the short story is that this claim also failed). 

So, to conclude

While expert testimony can play a key role in disputes, it is ultimately there to stengthen or weaken the legal arguments on which claims are based. Experts must always be conscious of their duty to assist the court, which means acting in an independant manner even when it runs contrary to the interests of the clients.

For more information about IT Group and our Expert Whitness service, contact us on 0845 226 0331 or email

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