Can a plaintiff bring a civil action against a state official for violating her constitutional rights under section 1983?

A plaintiff bringing a section 1983 action against a state official may not base liability on a theory of respondeat superior. See Ybarra v. Reno Thunderbird Mobile Home Village, 723 F.2d 675, 680 (9th Cir.1984). Thus, liability under section 1983 arises only upon a showing that the defendant personally participated in the acts. Taylor v. List, 880 F.2d 1040, 1045 (9th Cir.1989). A supervisor of a subordinate who violates a plaintiff's constitutional rights is liable only if the supervisor "participated in or directed the violations, or knew of the violations and failed to act to prevent them." Id.