Really, you people should read judicial decisions but here's my translation of the Judge's summary of the evidence at trial and the two sides' arguments:
1. Plaintiffs (those seeking to allow same-sex marriage) offered clear arguments and expert testimony on the violations of the Constitution created by enforcing Prop 8;
2. Proponents (of banning same-sex marriage) engaged in a lot of hand-waving rather than produce actual facts in support of their case, and their proposed experts weren't credible.
As a result, Proponents "failed to build a credible factual record to support their claim that Proposition 8 served a legitimate public interest."
The Judge finds that Prop 8 fails both rational-basis (legitimate public interest) and strict scrutiny (narrowly tailored to a compelling government interest), violating the Due Process Clause of the 14th Amendment and denying plaintiffs their fundamental right to marry.
The Judge's equal protection analysis notes "[w]hen a law creates a classification
but neither targets a suspect class nor burdens a fundamental right, the court presumes the law is valid and will uphold it as long as it is rationally related to some legitimate government interest." Marriage, however, is a fundamental right.
The Judge notes further: "Most laws subject to rational basis easily survive equal protection review, because a legitimate reason can nearly always be found for treating different groups in an unequal manner. See Romer, 517 US at 633. Yet, to survive rational basis review, a law must do more than disadvantage or otherwise harm a particular group. United States Department of Agriculture v Moreno, 413 US
528, 534 (1973)."
"Plaintiffs challenge Proposition 8 as violating the Equal Protection Clause because Proposition 8 discriminates both on the basis of sex and on the basis of sexual orientation. Sexual orientation discrimination can take the form of sex discrimination."
"Having considered the evidence, the relationship between sex and sexual orientation and the fact that Proposition 8 eliminates a right only a gay man or a lesbian would
exercise, the court determines that plaintiffs’ equal protection claim is based on sexual orientation, but this claim is equivalent to a claim of discrimination based on sex."
"The trial record shows that strict scrutiny is the appropriate standard of review to apply to legislative classifications based on sexual orientation. All classifications based on sexual orientation appear suspect, as the evidence shows that California would rarely, if ever, have a reason to categorize individuals based on their sexual orientation. FF 47. Here, however, strict scrutiny is unnecessary. Proposition 8 fails to survive even rational basis review."
"[T]he state cannot have an interest in disadvantaging an unpopular minority group simply because the group is unpopular."
"The evidence shows that, by every available metric, opposite-sex couples are not better than their same-sex counterparts; instead, as partners, parents and citizens, opposite-sex couples and same-sex couples are equal. FF 47-50. Proposition 8 violates the Equal Protection Clause because it does not treat them equally."
The Judge held that Prop 8 violated both the Equal Protection Clause and the Due Process Clause, and enjoined the government defendants (that's distinct from the proponents mentioned earlier) from applying or enforcing Proposition 8.
Go forth, my friends and family in California, and wed, if you will it.