The legal thriller is a sub-genre of thriller and crime fiction in which the major characters are lawyers and their employees. The system of justice itself is always a major part of these works, at times almost functioning as one of the characters. In this way, the legal system provides the framework for the legal thriller much as the system of modern police work does for the police procedural.

Usually, crusading lawyers become involved in proving their cases (usually their client's innocence of the crime of which he is accused, or the culpability of a corrupt corporation which has covered up its malfeasance until this point) to such an extent that they imperil their own interpersonal relationships and frequently, their own lives.