Preparation is the key to successful trial practice. Contrary to what you may see on television, no part of trying a case is extemporaneous. From opening statements, to cross-examination, to the objections one makes, to the impassioned closing argument attacking the credibility of an adverse witness, everything that is done and said in the courtroom is planned in advance.

In fact, apart from the preparation that an attorney has to do prior to a trial, it is considered beneficial even for expert witnesses to know about the legal issues involved in the case before  the trial. Expert witnesses are often recruited by the legal professionals such as the attorney and have the ability to testify more knowledge of a situation or topic as they are experts in certain topics and have specialized knowledge about it. In matters such as mental health or other areas such as social, experimental, cognitive, or developmental,  psychologists are called upon to testify. Despite claims that expert witnesses perform better if they are unfamiliar with legal problems outside of their own professional scopes, Simpson discounted such a hypothesis. He emphasises that understanding the specific legal requirements in a given instance provides each eununation and report a distinct purpose. He goes on to add that the more a psychologist learns about the law and the more information he acquires about a given case, the better he can execute his duty in court and so better serve the interests of justice. In his article, Daugherty (1960) discusses the significance of pre-trial preparation, claiming that it improves the competence of the court and attorneys, therefore speeding up the process of justice making. Similarly, Genzberger (1954) asserts that a well-prepared case is half won, and discusses how pre-trial preparation may benefit attorneys.