Alfred Kuba, founder of the Silicon Valley branch of In Defense of Animals, is suing the city of Vallejo, four Vallejo police officers and Six Flags Marine World for having him arrested during two animal rights protests in 2004.
Kuba claims the arrest violated his rights of free speech and freedom from unreasonable seizure.
In the most recent ruling in the case, U.S. District Judge William Shubb on Oct. 23 turned down the city's request to have the four officers dismissed as defendants on the ground that they were carrying out official duties.
Vallejo attorneys contended the officers were carrying out their responsibility to make an arrest after Marine World security officials had made a citizen's arrest and summoned police.
But Shubb ruled that police must determine whether a citizen's arrest was reasonable and whether any laws appear to have been broken before making an official arrest.
The judge wrote, "A police officer, however, is not entitled to hide behind a citizen's arrest in place of making a determination of whether probable cause exists."
The judge said the city hadn't proved it was reasonable to arrest Kuba "when he was on the public land and not violating any criminal statutes."
Kuba's attorney, Corey Evans, said his client was standing on a public sidewalk and a grassy area, holding a sign and passing out leaflets, during the two incidents.
Evans said, "He was doing things that were clearly constitutional. What is more at the center of constitutional rights than being able to hold a sign and hand out leaflets on public property?"
Mark Mazzaferro, public information officer for Vallejo, said he could not comment on the case because it is in litigation. A spokesman for Six Flags Marine World could not immediately be reached for comment.
The park is owned by Vallejo and operated by Six Flags Marine World under an agreement in which the city receives 20 percent of the net profits, Mazzaferro said.
In May, the judge granted a preliminary injunction allowing Kuba to protest peacefully outside the entrance to the park on Memorial Day weekend, which had been designated by Marine World as a blackout period for public assemblies because of the high volume of holiday traffic.
Evans said a trial in Shubb's court on Kuba's bid for financial damages will begin on Dec. 5. After the trial, the judge will conduct a separate proceeding to decide whether to issue a permanent injunction.