The subject matter of this chapter lies at the heart of the judicial process, and, perhaps for that reason, is one to which the rules of positive law seldom refer in explicit terms. It is more intractable than many: in the last resort it is concerned with the mental processes of the judge himself, and those processes cannot ordinarily be known save to the extent that the judge is willing to disclose them in his exposition of the reasons for his decision or in the course of the proceedings leading up to his decision. Nor is it possible rigidly and accurately to enforce such rules as there may be which purport to restrict use by the judge of knowledge that he happens to have: only an Orwellian ‘Thought Police’ equipped with futuristic ‘thought detection’ devices could do that. For the time being, only two means of control exist - a judge possessed of knowledge of which he cannot make legitimate use in a given case can be disqualified, and a decision which is seen to be based in part on such knowledge can be set aside by a court of appeal or cassation.

The inadequacy of these controls is shown in the report for France.