If you've been to enough large-scale public events in San Francisco parks, you've undoubtedly seen something that may have struck you as particularly ironic–a small, cordoned off area labeled a "free speech zone" where protestors, petitioners and pamphleteers are roped into if they want to openly push their agendas.
See, you can exercise your First Amendment rights all you'd like. You're just going to have to do it somewhere that doesn't block everyone's view of the stage.
The San Francisco Parks Code allows for free expression in most city parks. However, in 1981, the city placed geographic limitations on precisely where individuals are allowed to advocate for their causes in certain high-traffic locations.