In the Line of Duty 4: Witness is a 1989 Hong Kong action film directed by Yuen Woo-ping, starring Donnie Yen, Michael Wong and Cynthia Khan. The film was released in the Hong Kong on 21 July 1989. The film is nominally part of the loosely connected In the Line of Duty and Yes, Madam! series. The alternative titles of this and other films in the series can be cause for confusion.