The fact of the matter is that same-sex marriage will come in one of two ways [assuming it comes via the SCOTUS]: (1) as an Equal Protection judgment; (2) as a Full Faith & Credit judgment (assuming at least one state legalizes, first). Most likely the latter. Lawrence did neither, nor did Lawrence provide a precedent to either, nor was Lawrence any sort of necessary prelude to same-sex marriage...
The qualifier "necessary," isn't necessary. Granted, advocates of same-sex marriage my attempt to force this change on society via a number of avenues, but Lawrence is certainly one of them, and is a great benefit to their cause.
From Kennedy's majority opinion in Lawrence...
In Planned Parenthood of Southeastern Pa. v. Casey, 505 U. S. 833 (1992), the Court reaffirmed the substantive force of the liberty protected by the Due Process Clause. The Casey decision again confirmed that our laws and tradition afford constitutional protection to personal decisions relating to marriage, procreation, contraception, family relationships, child rearing, and education. Id. , at 851. In explaining the respect the Constitution demands for the autonomy of the person in making these choices, we stated as follows:
" These matters, involving the most intimate and personal choices a person may make in a lifetime, choices central to personal dignity and autonomy, are central to the liberty protected by the Fourteenth Amendment. At the heart of liberty is the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life. Beliefs about these matters could not define the attributes of personhood were they formed under compulsion of the State." Ibid.
Persons in a homosexual relationship may seek autonomy for these purposes, just as heterosexual persons do. The decision in Bowers would deny them this right.
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Bowers was not correct when it was decided, and it is not correct today. It ought not to remain binding precedent. Bowers v. Hardwick should be and now is overruled.
In Lawrence, the SCOTUS has held that Bowers denied to persons in homosexual relationships the Constitutional protection of their autonomy for the purposes of making "personal decisions relating to marriage, procreation, contraception, family relationships, child rearing, and education."
In Lawrence, the SCOTUS has further held that "the right to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life," is "at the heart of liberty," and in overruling Bowers has affirmed that this right may be excercised in the pursuit of homosexual self-definitions on an equal footing with that of hererosexuals. It's difficult to imagine that a right held to be "at the heart of liberty" could be held to be anything other than a fundamental right. The autonomy to make personal decisions regarding marriage has been explicitly encompassed in the overruling of Bowers by Lawrence.
Lawrence sets the table advantageously for the swiftest endgame possible for advocates of same-sex marriage.