SAN FRANCISCO — If any observers thought Judge Vaughn Walker would have a difficult time striking down Proposition 8 as unconstitutional, they were mistaken.

The San Francisco federal judge’s 136-page ruling today almost breezily concluded that the ballot measure defining marriage as one man and one woman did not pass constitutional muster. Walker ruled that Prop 8 violates Equal Protection and Due Process guarantees, and that gays and lesbians deserve extra constitutional protection — though they didn’t need it to prevail in this case.