The citizen is a public, not a private man. The Public is that area of life in which are performed all those acts which are not private, and which constitute our interaction with the State as well as with local authorities, and with public entities such as businesses.
I say that the citizen is first and foremost a public entity because the Public has always been privileged over the private in the West. This is because Westerners are by nature competitive and appetitive, and it is in the Public Sphere that the War of All against All (which is the proper state of Natural Man, supersed by the Public Peace of Political Man) is carried on by other means.
The Private is primarily that which is not covered by law. Every aspect of life as an individual, or as part of a family, which is considered to be personal and free from regulation, is part of the Private.
And I'm not talking about 'regulation' by custom, decorum, dictates of religion, utterances by TV talking heads and inane 'celebrities', or other such irrelevances. I'm talking about regulation by the State and it's agencies. The silence of the Law constitutes the Private, and the utterance of the State constitutes the Public. Go back to Plato's Republic where everything from childcare (children were to be taken from their parents at birth and reared by the State in institutions) to the Arts (actors were banned) was in the Public Sphere - and those formally engaged in that sphere were naturally of higher status in society than those not.
The West as a culture has always given more social importance to the formal obligation of the relationships of the Public Sphere than to the private opinions and practices of individuals. Especially in America, where the category of 'citizen' is based upon a formal, absolute equality of individuals before the State and its Law. An equality which is based upon the possession of a qualification granted by the State- rather than upon adherence to a creed, participation in some particular type of political structure, or on some biological characteristic.
The founding principle of the American Constitution is its definition of Man as something endowed with inalienable rights by his creator, which are to become political rights with the creation of the Constitution: life, liberty, and the pursuit of happiness.
No one has a right to life as a natural being, because the natural state of Man is conflict, where there is only strength, cunning, and chance, not right. It is the advent of the State which supresses this War of All against All, and allows the development of Law, Right, and Obligation, to take place. But the citizen of the new State created by the Constitution, did have and does have a right to his political life as a citizen - because the Constitution says he does. The Right to participate in the Public processes and activities of the State as these affect his perception of the General Good, and as they affect his personal comfort, well-being, purposes and ambitions as a private individual. And the Constitution says as much because these are the things that in the West, as a consequence of the appetitive, competitive nature of its people, constitute life, liberty and the pursuit of happiness.
Every Public process and status which is available to any citizen, in virtue solely of his being a citizen, must equally be open to every other citizen - otherwise the most fundamental right acknowledged by the Constitution, the right to political life is set aside.
Homosexuals want to bring about for themselves an institution which regulates sexual, social and economic behaviours in the same way that marriage regulates such behaviours for heterosexuals. They want to be married in the same way and with the same benefits and obligations that heterosexuals are married.
Personal opinion as to whether such an institution would be morally right, socially acceptable, ethically correct, are irrelevant to the question of whether one set of citizens is being denied participation in a public process to which other citizens have access. If, in a Republic based upon citizenship, where citizenship is understood as a formal qualification granted by the State, one aspect of life as a citizen is denied to a group that is in every way formally qualified to participate in it, then that denial is un-Constitutional.
Homosexuals wish to participate as citizens in a public relationship which regulates public issues of social, sexual and economic behaviour. There is already a means to regulate such issues, participated in by other citizens and sanctioned by the State. The institution of marriage.
Since every American homosexual is by definition an American citizen he has the right to participate in every aspect of Public life that heterosexual citizens participate in. Precisely because he is a citizen.
For those concerned about terminology, who might wish to differentiate the form of participation in a process from the right to participate, and therefore to enjoy the benefits designated by the State which follow from participation in that process, then 'civil union' might be a more acceptable term than 'marriage'.
The two would differ from each other only in description, not function.
Whether you call it marriage or civil union, and whatever your personal opinion as to its origin and purpose, it can't be denied that a social process exists that regulates sexual, social and economic behaviours. Nor can it be denied that one group of citizens (heterosexuals) have access to it while another group of citizens (homosexuals) does not.
That denial is un-Constitutional.
Like it or not, Queers have a right to marry.