A Introduction — Protecting Private and Public Interest in Litigation
The Matrix Churchill case, in which ministerial claims for public interest immunity were rejected and the accused acquitted,  has given rise to an intense controversy concerning ministers’ responsibilities in connection with public interest immunity. In addressing the issues raised by this case, we should not allow ourselves to be distracted from one fundamental and uncontroversial principle: that all relevant evidence is not only admissible but is also compellable. It is an axiomatic requirement of justice that litigants must have an opportunity to be heard. This implies not just an opportunity to put forward arguments but also an opportunity to place evidence before the court. For in factual controversies arguments without facts are just as sterile as arguments without authority in legal controversies. Accordingly, parties to litigation have a right to bring before the court all evidence relevant to their claims. It is a principle of general importance, Lord Hailsham explained, that ‘in all cases before them, the courts should insist on parties and witnesses disclosing the truth, the whole truth, and nothing but the truth, where this would assist the decision of the matters in dispute.’
The disclosure of the whole truth is as important to the administration of justice as it is to individual litigants. A judgment which is known to have been given not on the basis of all the available evidence but on only part thereof cannot inspire confidence in its correctness. The efficacy of the system of justice is in large measure a function of the confidence that it commands amongst the public at large. Such confidence is bound to be undermined by the knowledge that the courts systematically allow a party to litigation, or a third person who is in possession of relevant information, to withhold evidence from the court. Justice in such situations cannot be seen to be done.
We may therefore say that there is both a private interest and a public interest in the disclosure of all relevant evidence. The former is a function of the litigant’s entitlement to prosecute his cause. The latter is informed by the public interest in promoting an effective and just system of justice.
It has to be stressed, though, that the existence of a private and a public interest in full disclosure does not impose a duty on the courts to seek out all available evidence. In an adversarial system the parties are left to find their own evidence. Nor is the law of procedure obliged to arm litigants with all possible instruments for unearthing evidence. The law does not give private litigants a right to obtain
search warrants and ransack other people’s premises. Nor does the law provide a litigant with the power to compel third parties to hand over, before trial, the materials they have or divulge the information they possess. It is not a requirement of justice that all possible means for discovering the existence of evidence should be placed at the parties’ disposal.
This said, however, we are entitled to demand that the courts implement effectively and consistently the law’s existing commitment to the disclosure of evidence. This commitment may be gauged from the procedures that the common law and the rules of court provide for the discovery of evidence. For example, litigants may, under a subpoena, secure the attendance of witness and, under RSC Ord 24, demand from their opponents discovery of documents relevant to the issues in the case. Over the last decades the commitment of the law to a policy of securing the disclosure of all relevant evidence has increased very considerably. The courts have been prepared to allow pre-trial discovery against third parties in certain circumstances. This was followed by legislation contemplating further extension of third party disclosure. Perhaps the most remarkable indication of the courts’ interest in securing relevant evidence is the establishment of the Anton Piller procedure, whereby the court may order a litigant to allow his opponent’s solicitor to enter his premises, search for relevant evidence and seize it.
These developments provide concrete indications of the importance that the administration of justice attaches to the rendering of judgments on the basis of all available and relevant evidence. They suggest that the law is prepared to place the interest in securing evidence above, for instance, the convenience of third parties and above the demands of privacy of those who might be tempted to destroy evidence. Of course, the commitment to full disclosure is not absolute. Legal professional privilege, for example, confers immunity upon communications between lawyers and their clients. But the commitment to securing all evidence relevant to a dispute before the court is nevertheless a powerful and well- entrenched policy.
There is, however, one exception to this observation: public interest immunity. An examination of judicial decisions in this area provides ample reason for doubting the courts’ adherence to the idea that it is in the interests of justice that all relevant evidence should be made available in civil or criminal proceedings. It is not that the courts have qualified their commitment to the principle of full disclosure. On the contrary, the courts have stressed often enough that, in the final resort, the interests of justice must take precedence over whatever public benefit may be derived from suppression of certain types of information. But in practice the courts have condoned, under the excuse that it was in the public
interest to do so, suppression of evidence which was by any standard both relevant and important to the determination of truth. By doing so the courts have encouraged and tempted ministers, government departments and other public bodies to place obstacles in the way of private litigants seeking access to relevant evidence.
The doctrine that the courts are the sole arbiters of whether and when suppression of evidence is in the interests of justice has, paradoxically, encouraged ministers and public bodies to pay little or no regard to the interests of justice. Government ministers and other officials could legitimately reason that it is not for them but for the courts to decide whether justice required disclosure. Their task is limited to expressing the view that disclosure would be deleterious to the public interest. On their part, the courts have declined to place such claims under searching scrutiny, preferring to accept them at face value. Furthermore, the courts have shown a remarkable reluctance to investigate the effects that the withholding of evidence might have on the prospects of a litigant to prove his case and on their own ability to render correct judgments. These judicial attitudes have created fertile conditions for practices of the kind which the Scott inquiry has been investigating.
Chen Shamgar has assisted with the research for this article which has been facilitated by a grant from the Leverhulme Trust.
 See Leigh, Betrayed: The Real Story of the Matrix Churchill Trial (London: Bloomsbury, 1993); Tomkins, Public Interest Immunity after Matrix Churchill  PL 530.
 Glasgow Corpn v Central Land Board (1956) SC 1 (HL), 18— 19.
 Dv NSPCC  1 All ER 589, 600. See also Conway v Rimmer [ 1968] 1 All ER 874.
 See Devlin J’s view mentioned in Ellis v Home Office  2 All ER 149, 151.
© The Modern Law Review Limited 1994 (MLR 57:5, September). Published by Blackwell Publishers, 108 Cowley Road, Oxford 0X4 1JF and 238 Main Street, Cambridge, MA 02142. USA.
 Dworkin, A Matter of Principle (1985) ch 3, ‘Principles, Policies and Procedure,’ discusses the extent of the lawmaker’s duty to provide procedures that render correct results.
 Norwich Pharmacol Co v Customs and Excise Comrs  2 All ER 943; Bankers Trust Co v Shapiro  3 All ER 353.
 Supreme Court Act 1981, s 34(2); RSC Ord 24, r 7A.
 Anton Piller KG v Manufacturing Processes Ltd [ 1976] 1 All ER 779. See Dockray and Laddie, ‘Piller Problems’ (1990) 106 LQR 601.
 McNicol, Law of Privilege (New South Wales: The Law Book Co, 1992).
 For an exposition of the law, see Cross and Tapper, Cross on Evidence (London: Butterworths, 7th ed, 1990) ch XII; Aronson and Franklin, Review of Administrative Action (Sydney: Law Book Co, 1987) ch 13; Ligertwood, Australian Law of Evidence (Sydney: Butterworths, 2nd ed, 1993) 280. For the position in other common law jurisdictions, see Cox, ‘Executive Privilege’ (1974) 122 U Pa L Rev 1383; Berzins, ‘Crown Privilege: A Troubled Exclusionary Rule of Evidence’ (1984 — 85) 10 Queen’s U 134.