The litigation consultant and expert witness has a primary obligation to the truth and to his scientific profession, followed very closely by his obligation to his client. He is obliged to give his client his best judgement about the scientific aspects of the dispute as seen by both sides, their relationship with the law, how his client can best argue his case, not avoiding its scientific weaknesses, and how the opposing parties are likely to argue and what evidence and opinions they may present. When testifying, the expert witness must always give a truthful answer to any legitimate question that is asked, whichever side may benefit from the answer. However, the expert witness must always be conscious that law cases are adversarial proceedings in which the other side intends to ask questions in such sophisticated form that the question and a truthful, but unsophisticated, answer will put the expert's client's case in an unjustifiably bad light. Instead of the unsophisticated answer, the expert must give the sophisticated answer that fully transmits the scientific truth of the matter without the distortion introduced by the form of the question. Finally, the expert witness must know when to give the shortest truthful answer and when to expand his answer to introduce scientific subject matter that needs to be covered.
Being an expert witness is a very challenging aspect of a scientific profession.