According to British law, the test of negligence is "the standard of the ordinary skilled man exercising and professing that special skill. A man need not possess the highest expert skill; it is well established law that it is sufficient if he exercises the ordinary skill of an ordinary competent man exercising that particular art" (Bolam vs. Friern Hospital Management Committee).
Often, a client will hire a particular contractor because that contractor is considered an "expert" in the field. Should a higher standard of care be expected from this professional? British courts ruled that it is the duty of a professional person to exercise reasonable care in light of his or her actual knowledge. If the specialist had knowledge but acted in a way which ignored that knowledge and this ignorance led to personal injuries, then the specialist could be considered negligent. Since the expert assumedly had a much higher degree of training and experience in the field, it is likely that the expert has a greater level of knowledge on which to base his or her decisions. This decision was made apparently without regard to the above Bolam law, as the "expert" and Bolam laws apparently provide conflicting descriptions of negligence.