The legal admissibility of scientific tools, such as dendrochemistry providing forensic evidence for criminal or civil cases, critically relies on the quality of fundamental and applied scientific research. The "Daubert" and "Frye" criteria that federal courts in the U.S.A use for determining legal admissibility requires publication of the scientific basis for the tool, and general acceptance by the scientific community. The field of dendroforensics is rapidly evolving, with new methods constantly being developed. In this manuscript we investigate how this dendrochemical evidence has been used successfully in the courtroom. The study of tree rings using physical anatomical and dendrochronological methods has been used as evidence in courts for over 150 years. From these beginnings in dendroecology dendrochemical and biological methods have matured enough to allow it to be used in forensic investigations, finding applications as a new independent line of evidence around the world, supporting cases involving murder, trafficking of protected species, and pollution crimes. We summarize some of the key applications of dendrochemistry in forensic cases and illustrate them with courtroom examples. The basic analytical methods discussed (e.g., PCR, GC-MS, LIBS, LA/ICP-MS, EDXRF) are all conventional. However, for findings to be relevant to judicial cases, the data is normally applied with additional lines of evidence gathered such as tree physiology and relevant statistics. This can allow us to gain more powerful data to help age date a specific event or to spatially identify a source material. The purpose of this article is to show how recent research has paved the way for the use of dendrochemical evidence in courts. It shows how dendrochemistry can be useful for forensic investigations including: murder cases, trafficking of protected species, and pollution crimes. The applications are illustrated by several summarized legal cases, but due to the confidential nature of some of these cases it was not always possible to provide full details or references.

attempt to detoxify. This policy can result in substantial financial losses to farmers and other parties on whose property these contaminants are detected. If regulated levels are exceeded in one sample, the impacts are rarely limited to one area, or within the sampling period. It is therefore important to establish the extent of the contamination, distinguish the potential source(s) and identify the duration of the contamination event. These determinations are especially challenging to account for background noise or when multiple sources of these contaminants are present within a 10 kilometre (km) radius of the investigated area and could have contributed to the contamination. This manuscript examine potential pitfalls in the analysis of (PCBs), dioxins (PCDDs) and furans (PCDFs) in terms of their regulated levels, sampling challenges, the analysis of samples and statistical interpretation of the test data. 2 REGULATED LEVELS PCDD/F and PCBs are detected in the environment as complex mixtures. To assess the risks to human health and the environment, internationally agreed Toxic Equivalency Factors (TEFs) have been developed and are regularly updated by the World Health Organisation (WHO). The current TEFs are based on the findings of Van den Berg et al.