The Discovery Process is a means by which both the prosecution and the defense gain access to each other's investigatory information through request or other devices in order to prepare for the trial.
discovery is permitted only when the desired information is material to the preparation of the applicant's case or defense. Discovery is denied if the matter is irrelevant or if it comes within the protection of a privilege.
Most evidence is allowed under discovery, but some types are protected. The purpose of discovery is to allow both sides of the trial access to the same information so the trail itself can be as objective and fair as possible. If relevant information is held back, one side might end up with a subjective advantage during the trial. With discovery, most evidence can be examined and prepared by each side so they may best represent their positions. Discovery is dependent on each party having a clear course of action, and on the good faith of both parties; the court has the power to halt discovery if problems -- such as harassment -- arise.