Or, we could say that, this decision is that the federal government has no right to define marriage.
But is that really true? If I recall correctly, a Supreme Court decision in the late 1800s upheld a federal law which bans polygamy. It was a case dealing with Mormon plural marriage.
It just seems to me that, legally, the federal government should have a definition of marriage, because many areas of federal law depend on marital status. If this decision means that the federal government has to accept any definition of marriage, then I guess I’m lost on the reasoning.
That case involved the pre-statehood Utah territory. Congress has complete legislative jurisdiction over territories, but not over states.