I think it has something to do with whats not defined by the feds is left to the states. The supreme court didnt say that marriage is between one women and one man from what I understand only that defining it as such doesnt violate the constitution.
Thus it leaves the door open for states to define marriage b/c it wasnt defined by federal authorities. This is the problem though and the reason it will keep getting thrown back to the supreme court. When lower courts have multiple rulings that differ from one another dealing with federal questions(this isnt really a federal question but since it does deal with the federal govt taxes, registration etc. it could be put in federal court) they get bumped up to higher courts to try and solidify the rulings with one from a higher court.
you should know that simply b/c a higher court rules a certain way doesnt mean the lower courts are legally bound to rule on cases that way. Now those cases may get over turned in appeal and the judge look like an ass which is why alot of judges find the same way as others but doesnt mean they cant legally go against higher courts.
"stari decis" or something like that means let the decision stand
With regards to marriage, the lower courts that have legalized gay "marriage" have done so, claiming it violates its own state constitution, not the federal one.
You make a good point. State constitutions can be stricter than the federal one, providing that there's no direct contradiction (see the 2002 school voucher case, "Zellman v. Simmons-Harris". The ruling doesn't mandate school vouchers for all states or that such be allowed for use at religious schools; it merely states the parameters for a school voucher program, if religious school usage is included).
A lower court, however, (as it relates to marriage) can NOT rule that a marriage law is federally unconstitutional, since the US Supreme Court has said the exact opposite.
Nor can lower courts assume that more recent federal Supreme Court rulings trump earlier ones (the argument gay activists are making in the case against Prop. 8, claiming that the 1996 ruling in "Romer v. Evans" trumps the 1972 ruling in "Baker v. Nelson).