The breach of duty must be so bad as to be gross, i.e. criminal. This was defined in Adomako [1994] 3 All ER 79 as follows: having regard to the risk of death involved, was the conduct of the defendant so bad in all the circumstances as to amount to a criminal act or omission? The prosecution must prove the following two elements:
a) that the circumstances were such that a reasonably prudent person in the defendant's position would have foreseen a serious and obvious risk of death arising from the defendant's act or omission;
b) that the breach of duty was, in all the circumstances, so reprehensible and fell so far below the standards to be expected of a person in the defendant's position with his qualifications, experience and responsibilities that it amounted to a crime.