Here are two links, one on legitimate state interest --
State Interest -- and its rational basis test --
Rational Basis Test.
The federal appeals court, when deciding constitutionality of a state statute, judges to determine if the state has a
legitimate state interest in the matter, employing the rational basis test to aid in determination.
CA's Prop 8 was passed by the voters to amend the state Constitution. Such amending, affecting state statutes, can indeed be brought about by legislative action or ballot initiative in CA.
Reading these two links, it would seem on the surface that overturn on appeal all the way through the SCOTUS would be a slamdunk. There doesn't seem to be any rational reason why the state has a
legitimate reason to deny the equal protection guaranteed by the 14th Amendment to committed gay couples that would accrue to them from marriage.
However, legitimate state interest is not the first criteria to be applied in such matters; it is the second.
The first criteria is reasonable and customary subject applicablity. The reasonable and customary subject applicability test is used in law, science, etc., many disciplines, to determine if the matter at hand makes sense to examine further. This test keeps the court from wasting time on subsequent complex analysis that can occur deciding legitimate state interest when doing so would be substantively absurd.
In Brown v. Board the question first posed is whether it is reasonable and customary that the subject of both White and Black children were applicable to school attendance.
In Brown v. Board, it was thus first judged reasonable and customary from a subject applicability perspective that both White and Black kids attend school, in a classroom, with teachers, etc. Thus the matter qualified for the subsequent legitimate state interest test .. and it was found that the state did not have a legitimate state interest in witholding equal financial schooling support for Black kids that segregation caused. Thus, segregation was ended in the name of equal protection under the 14th Amendment, so that Black kids could have equal access to adequately funded and thereby quality schools.
But in the Prop 8 matter, the court in dealing with the reasonable and customary subject applicability matter must test if "a man and a woman as husband and wife" applies to the word marriage (like "do
White kids attend school" in the Brown v. Board case), and thus, conversely, if any other relationship applies to the word marriage (like "do
Black kids attend school" in the Brown v. Board case).
In the Brown v. Board case, the answer to both questions was yes, both White and Black kids attend school. Thus the case qualified to be further examined to see if the associated statutes needed to be overturned.
But in the Prop 8 case, the word marriage, by definition, simply does not apply to anyone other than "a man and a woman as husband and wife".
Thus because it fails the reasonable and customary subject applicability test, the case is to be rightly dropped at this point, and no further review for unconstitutionality is warranted.
Indeed, the Prop 8 matter is analagous to saying "a dog is {accurate description of a dog}". Then when challenged that the correct description of dog will unconstitutionally exclude cats for the purpose of letting cats participate in dog shows, the first test is whether the definition of dog is accurate and if anything other than that description is a dog. If the first test succeeds and the second test fails, then the challenge is aborted, as further analysis is irrelevant.
The legitimate state interest test is only applied if the issue at hand rationally warrants it as first determined by the reasonable and customary subject applicability test. In the Brown v. Board case it did; in the Prop 8 and dog-cat matters, it obviously doesn't.
Indeed, it would be absurd to argue legitimate state interest in letting cat owners enter their cats in dog shows, as cats aren't dogs. Such analysis would be an absurd waste of time.
And, likewise, it would be absurd to argue legitimate state interest in letting "a man and a man" or "a woman and a woman"get married, as neither are "a man and a woman", the only qualifiers for marriage.
That is why, sometime in the late 1960s/early 1970s, gay leaders began bombarding the media with oxymoronic (and thus intrinsically false) phrases like "SSM", "same sex marriage", "gay marriage", and the like. The purpose of doing so was to effect a form of mind-control such that after a couple of generations a greater segment of the population would not only be more comfortable hearing these oxymoronic statements, but that a sufficient number of people would actually erroneously think that "marriage" means other than in addition to "a man and a woman as husband and wife".
Though marriage never has and still doesn't, by definition, mean other than "a man and a woman as husband and wife", what's relevant now is whether the judges deciding Prop 8 and similar cases have been sufficiently, in effect, brainwashed into falsely thinking otherwise.
If so, they will erroneously state that Prop 8 passes the reasonable and customary subject applicability test, and then an essentially absurd legitimate state interest test will most likely irrationally overturn Prop 8.