Dubner

Robin Dubner (“Dubner”) appeals the district court’s decision for defendants after a bench trial in her 42 U.S.C. § 1983 claim for unlawful arrest against the City and County of San Francisco (“City”), police officers Narda Ziegler (“Ziegler”) and John Ehrlich (“Ehrlich”), and Chief of Police Fred Lau (“Lau”). The trial judge dismissed Dubner’s claim because she failed to prove Ziegler and Ehrlich were the officers who arrested her and, therefore, could not establish lack of probable cause for her arrest. Since Dubner could not prove the underlying constitutional violation, the trial judge concluded that the City could not be held liable under Monell v. Dep’t of Social Svcs., 436 U.S. 658 , 98 S.Ct. 2018 , 56 L.Ed.2d 611 (1978). We have jurisdiction under 28 U.S.C. § 1291 , and we affirm in part, reverse in part, and remand for further proceedings.

I. FACTUAL AND PROCEDURAL BACKGROUND

On October 7, 1996, the American College of Surgeons (“ACS”) held a conven *962 tion at the Moscone Convention Center in San Francisco. The Moscone Center is owned by the City of San Francisco. During the convention, ACS leased the entire facility and controlled who was allowed into the building.…