Democratic State Senator Leland Yee says he received an email message four weeks ago from someone claiming to be a sniper and vowing to assassinate him in the Capitol if he didn't drop the legislation.
Yee says the threat was unlike any others he's received in the past because of its detail.
"This was a rather deliberate and specific exact strategy as to how he was going to carry out that particular threat," says Yee. "As a psychologist I'm deeply concerned whenever I'm dealing with any individual talking about specifically how they're going to carry out a particular act."
Authorities have arrested 45-year-old Everett Basham of Santa Clara County.
He's charged with illegal possession of firearms, manufactured explosives and chemicals. He's also charged with threatening a dignitary.