Violation of department violations can’t reasonably be a § 1983 claim or violation of the Fourth Amendment. Estate of Biegert v. Molitor, 2020 U.S. App. LEXIS 24211 (7th Cir. July 31, 2020):
The estate also emphasizes that the officers violated police department regulations and that these violations bear on the officers’ reasonableness. But the district court was correct to give no weight to these arguments. As we have previously stated, § 1983 “protects plaintiffs from constitutional violations, not violations of state laws or, in this case, departmental regulations and police practices.” Scott v. Edinburg, 346 F.3d 752, 760 (7th Cir. 2003). Policies and procedures do not shed light on the reasonableness of an officer’s behavior because, “even if they could be practicably assessed by a judge, [such policies] vary from place to place and from time to time,” and so “[w]e cannot accept that the search and seizure protections of the Fourth Amendment are so variable.” Whren v. United States, 517 U.S. 806, 815 (1996).