ISO 21043-4:2025 PDF

This document specifies requirements and provides recommendations for the interpretation of observations to reach opinions that answer questions that are relevant for decision making in investigations or legal proceedings. This document states requirements that are applicable to all forensic disciplines. This document states requirements that apply when the opinion is based directly on human judgement and when the opinion is based on interpretation through a statistical model. This document is applicable to interpretation that occurs at a scene, within a facility, or within a judicial setting. This document establishes requirements designed to safeguard the process for the interpretation of observations including the use of either statistical models or human judgement, to address alternative propositions based on the questions asked by the customer. Interpretation is not necessary and the requirements of this document do not apply if the observations resulting from the analysis directly answer the relevant question. EXAMPLE In analytical chemistry, substances are often identified or classified. Provided that the applied analytical methods are not limited in selectivity or sensitivity for the given question, the observations can lead to a direct statement of the name of the substance (identification) or a type of material (classification). This is not considered interpretation for the purposes of this document.