Significance and Use
3.1 The goal of this guide is to reduce the incidence and impact of perjured testimony in administrative proceedings and in the criminal, civil and family court systems.
3.2 It is a mathematically established statistical principle that the probability of two independent events both occurring is the algebraic product of the probabilities of either event occurring alone.3
3.3 In litigation, the situation frequently arises:
3.3.1 That witnesses from opposite sides offer diametrically contradictory testimony regarding a fact or facts, such that one must almost certainly be lying, and
3.3.2 That witnesses from one side corroborate each other’s testimony, such that either both must be telling the truth, or both must be lying.
3.4 Where both witnesses are examined regarding a fact:
3.4.1 By PDD examiners who have personally established that the level of accuracy they are able to achieve meets or exceeds requirements established by the courts of the jurisdiction.
3.4.2 The results when taken together support a strong common inference about the respective deceptiveness of the subjects.
3.4.3 If the minimum accuracy is set at 86 %, the probability that the inference will be wrong is less than 2.00 %. If the minimum accuracy is set at 90 %, the probability that the inference will be wrong is no higher than 1.00 %.
3.5 When more than two witnesses are examined by such examiners about a fact and all results support a common inference about the deceptiveness of the subjects regarding that fact, the probability that the inference will be wrong is even lower, in accordance with the statistical principle.
3.6 The validity of this guide rests on evidence that competent examiners are personally capable of achieving sufficient accuracy.
3.6.1 Determination of examiners’ competence must be based not primarily on their training, years of experience, or the number of tests they have conducted, but on their personally demonstrated capability of the participating examiners.
3.7 The conditions and procedures outlined in this guide shall be known as the “Marin Protocol,” for the originator.4
Scope
1.1 This is a guide for the derivation of quantitative assessments of the credibility of proposed witness testimony through the application of established statistical principles to combinations of PDD examination results, and for the utilization of such assessments in the interests of justice (The Marin Protocol).
1.2 This guide describes circumstances in which proven statistical principles, applied to PDD results, can reliably quantify the trustworthiness or untrustworthiness of witness testimony, and
1.2.1 Delineates requirements necessary to effect the generation and practical use of such results, including:
1.2.1.1 Criteria regarding witnesses to be examined,
1.2.1.2 Criteria for determining facts upon which witnesses are to be examined,
1.2.1.3 Certification of examiners eligible to conduct examinations,
1.2.1.4 Combinations of results which support strong inferences, and
1.2.1.5 Appropriate uses to which strong inferences can be put.
1.3 Courts and others responsible for adjudicating questions of fact may choose whether and when to invoke paired PDD testing.
1.3.1 This guide expresses the rights and obligations of all participants in order to best serve the interests of justice when it is invoked.
1.3.2 Paired PDD testing must not be invoked in any case in any jurisdiction where to do so would violate the laws of that jurisdiction.
1.3.3 Adherence to these guidelines ensures that the conclusions reached will be valid.
1.4 This guide is directed to the proposed testimony of witnesses in criminal, civil, administrative and family court litigation, regarding factual claims, where
1.4.1 It is unlikely that the witnesses could be honestly mistaken, and
1.4.2 The facts in dispute are such that the case may hinge on whom the trier of fact believes; whenever,
1.4.3 Witnesses on opposite sides of a case offer contradictory testimony.
1.4.4 Two or more witnesses testifying for one side offer mutually corroborating testimony.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
