What is the test for determining whether a prison official discriminated against an inmate for their speech?

The second element, causation, requires showing that the prison official intended to take the adverse action out of retaliatory animus to silence and to punish the inmate, as opposed to for some other reason. Shephard v. Quillen, 840 F.3d 686, 689-91 (9th Cir. 2016). Evidence probative of retaliatory animus includes proximity in time between the protected speech and the alleged adverse action, the prison official's expressed opposition to the speech, and the prison official's proffered reason for the adverse action was false or pretextual. See id. at 690.