SAN FRANCISCO — A San Francisco Superior Court judge on Friday ruled that a Ropers, Majeski, Kohn & Bentley partner who uploaded a YouTube video reaching out to potential class action members can’t use California’s anti-SLAPP law to ward off a defamation suit.

In denying anti-SLAPP motions by partner Thomas Clarke Jr. and Ropers, Majeski, Judge Harold Kahn reasoned that Clarke’s allegedly defamatory YouTube comments against the maker of a dietary supplement amounted to an advertisement and thus fall short of being protected.