Plaintiff Stephen Chiari sued the City of San Mateo and Officer Leroy Becker after Becker arrested him for operating a vessel while under the influence of alcohol, a violation of California Harbors and Navigation Code section 655(b). Chiari alleged that Becker submitted a police report containing material misrepresentations of fact for the purpose of denying Chiari his constitutional rights, and that the report caused the charges to be filed against him.
Judge Maxine M. Chesney of the Northern District of California granted in part and denied in part the defendants' motion for summary judgment on April 17, 2026. The court held that Chiari raised a triable issue of material fact on the malicious prosecution claim, citing the Ninth Circuit's holding in Mills v. City of Covina for the elements of such a claim, and Blankenhorn v. City of Orange for the principle that a police officer who maliciously or recklessly makes false reports to the prosecutor may be held liable for damages incurred as a proximate result of those reports. Because genuine disputes of material fact remained, the court held that Officer Becker could not obtain summary judgment on qualified immunity grounds, relying on S.R. Nehad v. Browder for the proposition that genuine disputes of material fact preclude a grant of summary judgment on qualified immunity.
Chiari's other claims fared worse. The court granted summary judgment to defendants on the false arrest claim under section 655(a) — reckless or negligent operation of a vessel — holding that Chiari failed to raise a triable issue as to Officer Becker's probable cause. The false arrest ruling cascaded through two additional claims: the deprivation of property without due process claim and the state-law conversion claim both fell because they depended on the unlawfulness of the arrest.
The court also granted summary judgment on Chiari's Monell claim alleging that the City of San Mateo maintained an unconstitutional policy of arresting boaters for driving or boating under the influence based solely on the arrestee having a blood alcohol level of 0.04 on a preliminary alcohol screening test and having been involved in any type of collision. Although the court determined Chiari raised a triable issue as to whether such a policy existed, it held he failed to show the policy was the moving force behind his arrest, because the evidence was undisputed that the police report Becker filed expressly identified multiple additional factors — including an injury boat accident, Chiari's objective signs of intoxication, preliminary questions, and his performance on the field sobriety tests — as the basis for the arrest.
The malicious prosecution claim now proceeds toward trial.