THE RELATIONSHIP BETWEEN JUDGE AND EXPERT ARE USUALLY CORDIAL UNLESS THE JUDGE FEELS HIS POWER THREATENED BY THE EXPERT. IN ADDITION, FAIRNESS REQUIRES THAT THE EXPERT PRESENTS HIS FUNCTION UNAMBIGUOUSLY TO THE SUSPECT BECAUSE MANY SUSPECTS ARE WILLING TO COOPERATE AGAINST THEIR OWN INTERESTS MERELY TO INTERRUPT THE MONOTONY OF PRISON LIFE. THE SUSPECT'S RIGHT TO READ THE PSYCHIATRIST'S REPORT CREATES A PROBLEM, SINCE MANY SUSPECTS ARE UNAWARE OF THEIR MENTAL CONDITION AND THE EXPERT MUST AVOID SHOCKING THEM. FURTHER, EXPERT WITNESSES AND DEFENSE ATTORNEYS SHOULD AND AVOID FRIENDSHIPS. EXPERT WITNESSES SHOUD EXPRESS THEMSELVES CLEARLY AND SIMPLY IN COURT; SOMETIMES THE UNFAMILIARITY OF THE JUDGE WITH THE NECESSARY TECHNICAL VOCABULARY MAKES COMMUNICATION DIFFICULT. THE EXPERT WITNESS SHOULD CHOOSE HIS WORDS CAREFULLY SINCE THE JUDGE MAY INTERPRET AN EVALUATION OF 'NOT INSANE' AS IMPLYING NORMALCY. TWO EXPERT WITNESSES SHOULD BE USED AT ALL TIMES, ALTHOUGH JUDGES OFTEN MISTAKENLY BELIEVE THAT REQUIRING ONLY ONE WITNESS WILL SPEED UP THE REPORT. BECAUSE EXPERT WITNESSES CALLED TO TESTIFY AGAINST COLLEAGUES IN MALPRACTICE SUITS FACE THE MOST DIFFICULTIES, THEY COULD FEEL FREE TO REFUSE TO TESTIFY IF THE COLLEAGUE IS AN ACQUAINTANCE. FOOTNOTES ARE INCLUDED. --IN FRENCH.