Proposition 22 was a law enacted by california voters in march 2000 to restrict marriage to opposite-sex couples. in may 2008, it was struck down by the california supreme court as contrary to the state constitution. the act was proposed by means of the initiative process. it was authored by state senator william "pete" knight and is known informally as the knight initiative. voters adopted the measure on march 7, 2000, with 61% in favor to 39% against. the margin of victory surprised many, since a field poll immediately prior to the election estimated support at 53%, with 40% against and 7% undecided. the act added section 308.5 of the family code, which read "only marriage between a man and a woman is valid or recognized in california". because the act was an ordinary statute, it could be struck down if it were inconsistent with the state constitution, as happened on may 15, 2008, when the state supreme court, ruling in in re marriage cases, declared that same-sex couples had a constitutional right to marry. this 4–3 decision invalidated proposition 22 and some related california laws. proposition 22 provoked debate long after its passage. in november 2008 california voters overturned the in re marriage cases decision by approving an amendment of the state constitution called proposition 8. in june 2010, proposition 8 was declared unconstitutional by u.s district judge vaughn walker based on the due process and equal protection clauses of the fourteenth amendment of the united states constitution. in june 2013, the united states supreme court in hollingsworth v. perry ruled that the intervenor-defendants had no article iii standing to appeal walker's ruling, keeping proposition 8 unforceable throughout california and enabling same-sex marriage to resume just two days after the decision.