legal aspects of forensic science are all about the Constitutional and other legal constraints on how a criminal investigation can be carried out. These include discovery, search and seizure, protection against self-incrimination, and due process. The production of evidence at a trial is compelled by a subpoena, and order to appear in court. The admissibility of evidence is controlled by a set of rules that govern the security of the evidence, authenticity, relevance, and other issues. Scientific evidence is subject to all of these constraints as well as some that apply only to this type of evidence.