Qualified immunity is a doctrine that was established by the U.S. Supreme Court in the 1967 case Pierson v. Ray. Repeated Supreme Court decisions have expanded on the idea. Reuters in May noted that it has "become a highly effective shield in thousands of lawsuits seeking to hold cops accountable when they are accused of using excessive force." In the wake of recent protests against police brutality, the legal principle is getting renewed attention from the public and legislators.
The Pierson v. Ray decision allowed government officials immunity from lawsuits alleging civil rights violations if the official was acting in “good faith.” Subsequent cases have make it increasingly harder for plaintiffs even to bring a case against a public official.