8.2 Concerning the substance of Mr. Collins1 allegations, the Committee regrets that several requests for clarifications notwithstanding (requests which were reiterated in two interlocutory decisions adopted after the decision on a&missibility of 2 Kovember 1988), the State party has confined itself to the observation that the facts relied upon by the author seek to raise issues of facts and evidence that the Committee is not competent to evaluate. The Committee cannot but interpret this as the State party's refusal to cooperate under article 4, paragraph 2, of the Optional Protocol. Article 4, paragraph 2, of the Optional Protocol enjoins a State party to investigate in good faith all the allegations of violations of the Covenant made against it and its judicial authorities, and to make available to the Committee all the information at its disposal. The summary dismissal of the author's allegations, as in the present case, does not meet the requirements of article 4, paragraph 2. In the circumstances, due weight must be given to the author's allegations, to the extent that they have been credibly substantiated. 8.3 The Committee does not accept the State party's contention that the communication merely seeks to raise issues of facts and evidence which the Committee does not have the competence to evaluate. It is the Committee's established jurisprudence that it is in principle for the appellate courts of States parties to the Covenant to evaluate facts and evidence in a particular case or to review specific instructions to the jury by the judge, unless it can be ascertained that the instructions to the jury were clearly arbitrary or amounted to a denial of justice, or that the judge clearly violated his obligation of impartiality, d/ In the present case, the Committee has been requested to examine matters in this latter category. After careful consideration of the material before it, the Committee cannot conclude that the remark attributed to Justice G. in the committal proceedings before the Portland Magistrates Court resulted in a denial of justice for Mr. Collins during his retrial in the Home Circuit Court of Kingston. The author has not even alleged in which respect the instructions given by the judge to the jury were either arbitrary or reflected partiality. The Committee further notes that the verdict of the jury necessarily entailed a mandatory death sentence, by which the judge was bound. Secondly, the Committee notes that, although the author states that he apprised his counsel of the judge's alleged bias towards him, counsel opined that it was preferable to let the trial proceed. Nor was the matter raised on appeal, although the author's case was at all times in the hands of a professional adviser. Even if the remark was indeed made, in the absence of clear evidence of professional negligence on the part of counsel, it is not for the Committee to question the latter's professional judgement. In the circumstances, the Committee finds no violation of article 14, paragraphs 1 and 2. 8.4 Similar considerations apply to the alleged attempts at jury tampering by the investigating officer in the case. In a trial by jury, the necessity to evaluate facts and evidence independently and impartially also applies to the jury; it is important that all the jurors be placed in a position in which they may assess the facts and the evidence in an objective manner, so as to be able to return a just verdict. On the other hand, the Committee observes that where alleged improprieties in the behaviour of jurors or attempts at jury tampering come to the knowledge of either of the parties, these alleged improprieties should have been challenged before the court. In. the present case, the author claims that his counsel was informed, on 27 October 1983, -228-