[I just submitted this to Alternet.org]
There is one right that all marriages should have that same-sex couples should not have: the right to conceive children together, to create genetically related offspring from the couple's own genes.
Attempting to create children by joining the genes of two men or two women is radically unethical and unnecessary and is a wrong-headed goal and a mis-use of resources. It requires genetic modification to reverse the epigenetic imprinting that makes male and female gametes complementary so they can join together to make a new human genome. It is not just a new form of IVF, it is a radical push into genetic engineering of human beings that should not be allowed, not just because of the high risk of genetic defects in the child, but primarily because of how it would effect society and individual reproduction rights if we allowed people to be created from engineered genomes.
But it is currently legal, and many researchers are working on techniques to enable same-sex couples to conceive using stem-cell derived gametes. And though most same-sex couples are not the least bit interested in having their children be guinea pigs and do not feel that shared biological connections are required to have a loving family, there are also many that are eager to try it. It is not science fiction, it is perhaps just a year or two away from being attempted by a reckless lab and an emotionally manipulated couple.
Congress should ban cloning, same-sex conception, and other forms of human genetic engineering with an "egg and sperm law" that would prohibit conceiving children by any means other than joining an egg of a woman and a sperm of a man, unadulterated and unmodified so that they are truly "of" the person.
This ban would create a distinction in the rights of same-sex couples and man-woman couples that should match the distinction between marriages and civil unions: marriages should guarantee the couple the right to attempt to conceive children together, civil unions should be defined by states as being exactly like marriage except lacking conception rights.
At the same time they enact the "egg and sperm" anti-cloning law, Congress should make two more additional laws. The second law would be to recognize state civil unions as marriages for all federal purposes, if the state civil union is defined as being exactly like marriage except lacking conception rights. This would provide states with uniform Civil Union language that would make it possible to enact CU's in all fifty states, even those that have prohibited giving same-sex couples the rights of marriage in their constitutions. The third law would define in federal law that no marriage in the United States can be prohibited from attempting to conceive children using the couple's own genes, and affirm that all people have an equal right to marry and procreate. Together, these laws would truly preserve marriage, while also limiting it to a man and a woman.
These three laws make up "The Egg and Sperm Civil Union Compromise" and should be enacted immediately. There is no reason to wait, and doing it before the election will allow people to be free to vote on other issues rather than being held hostage to their position in the marriage debate.