What is an expert witnesses?

An expert witness provides an independent testimony on a case as a third party.  On the other hand, a fact (or “lay”) witness is an actor of the case who provides information about events as he has experienced. 

An expert witness grounds his analysis solely on the facts, as presented to and requested by him. The expert witness’ deposition and testimony are therefore unbiased. The expert expresses his independent deposition/testimony/opinion/views in a purely objective and rational manner. The expert witness’s role is to “seek an speak the truth” – the motto of the Securities Expert Roundtable.

An expert must produce a written and signed expert report, which demonstrates his/her positions. Such a witness report is bound to high levels of integrity, as well as strong legal standards. Like fact witnesses, the expert is compelled to deposition and testimony. The expert’s background is also subject to scrupulous reviews and expectations, in both its professional and its persona dimensions (his own personal life).

An expert’s testimony and deposition must be “based on sufficient facts, data or products”, and must also be “based on verifiable methods and principles“. Simply said, his expert report, his testimony and his deposition should be based on demonstrated facts and reality, not his impressions. The expert report is ground in facts, as well as a recognized and accepted methodology.

The expert witness must be “qualified by knowledge, skill, experience or education”. The ‘Daubert Standard‘ is the benchmark for the qualifications and competency of the expert witness in the federal US system. Standards varies by states and jurisdictions.  

An expert’s deposition, testimony and report are critical in high-stales litigation. As such the expert must also be able to explain, convey and convince his audience of their accuracies in highly challenging, confrontational and charged environments. His personal and human skills are often as valuable as his factual and cartesian analytical skills. 

Additional references

• Daubert standards

• Expert Witness Testimony – United States and Canada (Who’s Who Legal)