The Supreme Court ruled in Rehberg v. Paulk, 566 U.S. 356 (2012), there is absolute immunity for any grand jury witness, law enforcement or otherwise, from any civil action derived from their grand jury testimony, even if the grand jury testimony was knowingly or recklessly false or even where law enforcement officers have "conspired to present false testimony." This is, as some courts have observed, a harsh result and the Sixth Circuit questioned in Sanders v. Jones, 845 F3d 721 (6th Cir. 2017), "whether malicious prosecution remains a viable claim" after Rehberg in light of the difficulty it creates of overcoming the presumption of probable cause created by an indictment. The Sixth Circuit Squarely answered the question recently in King v. Harwood.
The Sixth Circuit concluded that malicious prosecution remains a viable claim even where there has been a grand jury indictment but only in the most limited of circumstances:
We hold that where (1) a law-enforcement officer, in the course of setting a prosecution in motion, either knowingly or recklessly makes false statements (such as in affidavits or investigative reports) or falsifies or fabricates evidence; (2) the false statements and evidence, together with any concomitant misleading omissions, are material to the ultimate prosecution of the plaintiff; and (3) the false statements, evidence, and omissions do not consist solely of grand jury testimony or preparation for that testimony (where preparation has a meaning broad enough to encompass conspiring to commit perjury before the grand jury), the presumption that the grand jury indictment is evidence of probable cause is rebuttable and not conclusive.