Forensic Toxicology has evolved greatly in recent years and today it plays a vital role in courts and other public forums throughout the world, with the potential to resolve the outcomes in criminal, coronial and civil investigations. The field of forensic toxicology is very broad, including analyses of drugs of abuse, clinical toxicology, drugs abuse in sport, alcohol drugs and driving, post-mortem toxicology. In this study we will give an overview of the existing usage and guidelines of forensic toxicology in United Kingdom. Forensic toxicology has evolved throughout the centuries and has now become a multidisciplinary and highly specialized tool in UK to investigate a wide range of scenarios but mainly involving the potential effects of drugs and chemicals on humans and animals. In these investigations, the three main objectives are to considered such as establishment of if toxicants are present and capable of contributing to death, if toxicants are present and capable of causing behavioural changes and if substances are present and whether or not they represent legitimate use or exposure. The main quality standards and protocols used in the analytical sector are published by ISO and ISO/IEC. These guidelines have implemented the general principles established transnationally and exemplify an overview of the best practice services in the UK. They also used as the basis for new European guidelines for best practice.43 territorial police forces in England and Wales purchase forensic services from private sector companies or service delivered to them by in-house police laboratories.