Samuel Landis, a Drug Enforcement Administration agent, was conducting routine surveillance on a suspected drug trafficker in a residential area of Salem, Oregon. Agent Landis ran a stop sign and struck a bicyclist who had the right of way, killing the bicyclist. A grand jury indicted him for criminally negligent homicide. Landis moved the case to federal court and claimed that he was immune from the state prosecution under the Constitution’s Supremacy Clause. The district court held that he was immune because he was acting within the scope of his job and his belief that he had to “drive with a purpose” to catch up with the other members of his surveillance team was “objectively reasonable.” The Ninth Circuit panel upheld the decision, and the State of Oregon sought rehearing of the case by the full Ninth Circuit.

In February 2026, the Constitutional Accountability Center filed an amicus brief on behalf of law professor Michael J.Z. Mannheimer, in support of the state’s petition for rehearing en banc. Our brief explains why Agent Landis is not immune from prosecution.

Properly understood, the Supremacy Clause permits federal courts to halt state prosecutions of a federal officer only when the evidence could not support a conviction. The 1890 Supreme Court case In re Neagle, the origin of what lower courts later termed “Supremacy Clause immunity,” contemplated only a limited gatekeeping role for federal courts: simply determining whether there is sufficient evidence of guilt under state law for a prosecution to proceed. That gatekeeping role prevents states from harassing federal officers through spurious prosecutions, but it does not empower federal courts to decide for themselves what conduct is “reasonable” without reference to state law.

Yet decisions in the Ninth Circuit have misread Neagle by ignoring state law, resolving factual disputes, and dismissing criminal charges based on the courts’ own sense of reasonableness. The Ninth Circuit has incorrectly interpreted Neagle as establishing a two-part test for Supremacy Clause immunity. First, the officers must have been acting within the scope of their federal duties. Second, their actions must have been “both subjectively and objectively reasonable.” This test misinterprets Neagle as establishing a federal reasonableness standard for immunity, when the decision instead analyzed whether the federal officer being prosecuted there had a justification defense under California law. Under Neagle, federal court intervention is warranted only if the facts are undisputed and no rational jury could find the federal officer guilty under state law. The Ninth Circuit should revisit the panel’s erroneous decision.