From the Introduction: "In fulfilling its mission, CBP [Customs and Border Protection] and its employees must sustain the trust and confidence of the public they serve. All employees must maintain high standards of honesty, integrity, impartiality, character, and professionalism to ensure the proper performance of government business and the continued trust and confidence of the public. The conduct of CBP employees must reflect the qualities of integrity and loyalty to the United States; a sense of responsibility for the public trust; courtesy and promptness in dealing with and serving the public; and a standard of personal behavior that reflects positively upon, and will be a credit to, both CBP and its employees."
U.S. Customs and Border Protection Directive No.51735-013B
U.S. Customs and Border Protection: https://www.cbp.gov/