It is the duty of every member of the Police Department to conduct himself or herself in a proper and law abiding manner and at all times to avoid the use of unnecessary force. Any member shall appear whenever necessary as a witness in a prosecution for a violation of an ordinance, statute or federal law, and no member shall retain any fee for service as a witness in any such suit or action to which the city is a party; any fees paid for such services shall be turned over to the City Treasurer.
(‘82 Code, § 2.28.050)