A litigation expert witness is someone whose knowledge and experience enable him or her to offer credible opinions and explanations in a lawsuit. Depending on the case and its jurisdiction, an expert witness may be called to advise the legal team of either plaintiff or defendant, may advise a judge about technical matters, or may actually testify in court. The qualifications to become a litigation expert witness tend to vary by case, though in some places courts are free to disqualify a so-called expert witness if the court does not believe that the person has either expertise or integrity.
While lawyers and judges are experts in the law, they often do not have deep knowledge of the many complicated matters that arise in the courtroom. Similarly, members of a jury may have difficulty deciding a case if they are unfamiliar with the significance of different types of evidence or have difficulty understanding the claims made by the legal representatives of the parties involved. A good expert witness should be able to explain complex issues to those without expertise so that they can use the information to properly argue and decide a legal case.
Becoming a litigation expert witness is usually a matter of having provable, in-depth knowledge and experience of a particular subject matter. For example, a medical or legal malpractice expert witness would usually be expected to hold appropriate educational credentials, such as a medical or law degree. In addition, the expert witness would likely need to demonstrate that she has experience in her field, either in the form of employment or some sort of published research. Litigation expert witness qualifications may vary widely depending on the subject that the courts, attorneys, and jury need to know more about. If a case involves a problem with an automobile, an expert witness may be a very experienced mechanic who only holds a high-school diploma, whereas a mental health expert witness would likely need to hold a doctorate degree.
The role of a litigation expert witness is typically defined by the needs and rules of a court. In some countries, expert witnesses primarily advise judges on complex cases, while in others, expert witnesses can be hired by either the plaintiff or defendant to bolster his case. In the United States, it is not uncommon for lawyers to hire an expert witness, not to appear in court, but to advise the legal team of any holes in their client's case before the case even reaches a courtroom.