The U.S. Supreme Court has held unconstitutional employment practices that unduly restrict political speech and overt political activities. Lower court cases show that the first amendment gives employees the fundamental right to engage in overt political expression and that employees cannot be subject to adverse employment action motivated by constitutionally protected political expression. Four major defenses have been successfully used by police supervisors sued for violating first amendment rights of subordinates to engage in overt political expression: (1) failing to show employee political expression is protected under the first amendment; (2) showing employer interest in efficient and effective service delivery outweighs employee interest in commenting on matters of public concern; (3) failing to show protected political expression is a substantial or motivating factor in police conduct; and (4) showing the police supervisor would respond in the same way in the absence of protected political expression. The author concludes law enforcement supervisors frequently hold political views in conflict with those of their subordinates, more information is needed about potential police civil liability for first amendment violations, and police supervisors need to be educated about liability risks of retaliating against subordinates who engage in protected political speech. 118 references, 21 notes, and 1 figure