Abstract:
The rule of law involving the privilege for witness causes certain classes of people to have some special rights a) not to be compelled to appear at a trial as a witness, b) to avoid taking oath before testify, c) not to testify at all, or d) not to testify in certain issue. Since this rule of law has a purpose to protect certain societal value which is more important than the fact finding from the witness although granting the privilege will affect fact finding process in the case especially criminal case which will have great impact on the rights and liberty of the defendant, to choose not to grant privilege to witness with certain status will result in more damage to the society. Therefore, many countries choose to enact the rule of law that grants privilege to witness who has special status or who is under special duty. Thailand grants witness privilege to the King, the Queen, the Heir apparent to the throne, the regent, diplomat, Buddhist monk and person who have certain occupation. The study found that granting witness privilege in criminal case because of the status of the person in Thai law still has many problems which are; a) Granting witness privilege to Buddhist monks violates the principle of equality and also increases the chance of avoiding law. b) Granting witness privilege to person in some occupations has no appropriate boundary. c) The law doesnt grant witness privilege to person who has close relationship with the defendant. Therefore, this thesis comparatively studies the witness privilege in criminal trial according to the law of Thailand, United Kingdom, United States of America, Japan and France to analyze and develop the law of Thailand.