The expert witness in civil cases must be able to demonstrate expertise on the specific matters that the court is considering. There are different kinds of witnesses who may give evidence in court proceedings. Sometimes mental health professionals are called as witnesses of fact to testify about, for example, whether someone was offered treatment, how often they attended the clinic and whether the treatment had any benefits. There are some differences in court procedures and in the requirements for expert witnesses across the United Kingdom. The implications of these for expert witnesses in Scotland and Northern Ireland are helpfully described in the British Medical Association guidance. In addition to the protocols and guidance produced by legal authorities in different countries, professional associations also offer and provide guidance for their members when acting as expert witnesses.