Insofar as the federal government is concerned, marriage is not about an emotional or spiritual or sexual union, but about rights and duties of couples as financial, even commercial entities. A traditional marriage has, as part of its ritual and as part of its financial contract (including legal rights and responsibilities of offspring), a legal registry in a courthouse somewhere. But same-sex partnerships have no such legal registry and therefore no such legally acknowledged contract. Some states have repaired this problem by legalizing these partnerships through a "marriage" registry, that then gives that couple states' rights--hospital visits, adoption privileges, tax exemptions, etc. Federal "registry" would give same-sex couple national privileges and responsibility, and would eliminate awkwardnesses at state borders. A same-sex couple would be treated so in federal taxation also. The controversy is really linguistic--does the word "marriage" belong to religions? Or is it simply a word in the English language meaning any joining of two or more elements?