Can a prosecutor be sued if they prosecute and lose based on one persons word against another?

Answer 1

Anyone can be sued. HOWEVER government employee's (prosecutors included) share what is called "qualified immunity". IN SHORT: qualified immunity shields government employees from civil and criminal actions.Qualified immunity is a doctrine in U.S. federal law that arises in cases brought against state officials under 42 U.S.C. Section 1983 and against federal officials under Bivens v. Six Unknown Named Agents, 403 U.S. 388 (1971). Qualified immunity shields government officials from liability for the violation of an individual's federal constitutional rights. This grant of immunity is available to state or federal employees performing discretionary functions where their actions, even if later found to be unlawful, did not violate "clearly established law." The defense of qualified immunity was created by the U.S. Supreme Court, replacing a court's inquiry into a defendant's subjective state of mind with an inquiry into the objective reasonableness of the contested action. A government agent's liability in a federal civil rights lawsuit now no longer turns upon whether the defendant acted with "malice," but on whether a hypothetical reasonable person in the defendant's position would have known that his actions violated clearly established law. As outlined by the Supreme Court in Harlow v. Fitzgerald, 457 U.S. 800 (1982),[1] qualified immunity is designed to shield government officials from actions "insofar as their conduct does not violate clearly established statutory or constitutional rights of which a reasonable person would have known."