Scientific Evidence In International Criminal Proceedings

In international criminal proceedings, scientific knowledge plays a significant role in gathering evidence that enables the establishment of factual truths. The use of specialized, often innovative research methods contributes substantially to the effective prosecution and conviction of perpetrators of international law crimes. International tribunal judgments are characterized by a high degree of complexity and diversity in the issues considered,which necessitates the use of so-called (scientific evidence). This evidence is provided by experts as part of their opinions.

It is emphasized in the literature that the discussed category of evidence is based on the achievements of various scientific disciplines, verified both in theory and in forensic practice. It also refers to expert opinions derived from new research methods, often still in the process of development and verification. It is important to note that the introduction of scientific evidence into international criminal proceedings is widely accepted and essential for achieving its objectives.

Expert opinions offer specialized knowledge beyond everyday experience and knowledge. The rapid development of forensic science has expanded the scope of expert research capabilities and has significantly improved the precision and conclusiveness of findings presented to judicial bodies.

It is also worth noting the differences in the presentation of expert evidence in international criminal tribunals compared to domestic criminal proceedings:

A. In international criminal cases, evidence collection is often hindered by ongoing armed conflicts. Without the cooperation of multiple states, a significant portion of the evidence may be destroyed or distorted.

B. International criminal tribunals employ a model that combines elements from various legal systems, particularly referring to continental law traditions and solutions adopted in common law systems.

The standard for assessing the value of scientific evidence always poses a significant challenge for judicial bodies. Modern legal proceedings distinguish three legal systems concerning the verification of scientific evidence:

1. a conservative system which does not admit new scientific evidence or does so in a very limited manner, protecting the criminal process against pseudo-scientific evidence, but at the same time preventing the use of new scientific advancements (e.g., in the Netherlands and Germany);

2. a liberal system which allows new scientific evidence provided specific criteria are met (e.g., in the United States);

3. a systems which lacks specific and general rules regarding the admissibility of new scientific evidence (e.g., Polish legal system).

It is crucial to select appropriate criteria when assessing the probative value of expert opinions based on specialized research methods. Special attention should be given to the standard established in the U.S. legal system, particularly the so-called Daubert Standard. The 1993 U.S. Supreme Court ruling in Daubert v. Merrell Dow Pharmaceuticals introduced criteria for evaluating the probative value of scientific evidence, including:

a. falsifiability,  the research method must be subject to verification through independent scientific research.

b. review and publication, the method should have been published and subjected to scientific evaluation in specialized literature.

c. diagnostic value, the method should have a specified error rate.

d. standardization, the method should have a developed standardized methodology.

e. general acceptance, the method should be accepted by the scientific community.

These American criteria are intended to ensure a thorough evaluation of judicial expertise, enabling judicial bodies to distinguish between scientific and pseudo-scientific methods.

The authors of the report "Scientific Evidence in Europe" identified four criteria for assessing scientific evidence in English law:

1. the subject of the opinion must extend beyond the common knowledge and experience of the judicial body,

2. the opinion concerns an area that is sufficiently well-organized and recognized as a reliable source of knowledge, and it is the speciality of an expert helping the court to reach the truth,

3. the expert must have acquired sufficient knowledge through study or experience to make their opinion useful to the court,

4. the expert must be impartial.

Similarly, the Dutch Supreme Court (Hooge Raad) in 1998 indicated that significant criteria for assessing scientific evidence include: the general principles of the discipline, the theoretical justification of the method used, the probative and diagnostic value (reliability and validity) of the method, and the qualifications of the expert.

Polish case law has not developed a general standard for the admissibility and evaluation of scientific evidence. However, based on the jurisprudence of the Supreme Court, the following criteria should be indicated:

• sufficient certainty of scientific research results,

• consistency and general acceptance of the method,

• methodological impeccability of the method,

• certification of the laboratory,

• identification by a recognized research institution,

• the research method should result from an accepted scientific theory, and when applying it, the strict adherence to research rules that guarantee accurate results must be followed.

Therefore, the literature on the subject rightly emphasizes that the assessment standards should be based on a wide range of criteria, which include:

1. reliability of the research method,

2. the research procedure applied,

3. the tools used in the research,

4. an assessment of how widely the research method is used in other countries, particularly those with leading forensic science and human rights protection,

5. the diagnostic value of the method, including a known and described error rate and the factors influencing incorrect results,

6. whether the research method is sufficiently described in the relevant scientific literature,

7. the appropriate qualifications of the expert interpreting the research results.

The final assessment of the expert's opinion is always made by the court adjudicating the case, with the key requirement being the skillful application of a wide range of criteria that ensure the research method qualifies as unquestionable scientific evidence.

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