The argument for this is fairly straightforward, and I am interested to see how proponents of prop 8 would challenge the crucial steps (if they can).
*] If proposition 8 discriminates on the basis of sexual orientation, and the discrimination is unjustified, then it violates equal protection.
*] Proposition 8 discriminates on the basis of sexual orientation (by allowing heterosexuals, but not homosexuals, to marry their partners).
*]The discrimination is unjustified.
*]Therefore, proposition 8 violates equal protection.
The only real dispute here is (3), but so far, I have not seen any convincing argument to justify the discrimination against homosexuals who wish to marry their partners. The form of the justification must specify some purported harm that same-sex marriage would cause to society. In other words, allowing same-sex marriage would cause “x, y, and z,” where “x, y, and z” are bad for society, and therefore the discrimination is justified. However, the trick is for prop 8 proponents to spell out what the “x, y,and z” consequences are and provide the evidence for them. Can anyone actually do this?