Highlights from today's Supreme Court arguments on Proposition 8, California’s ban on same-sex marriage.

JUSTICE ELENA KAGAN: Suppose a state said that, because we think that the focus of marriage really should be on procreation, we are not going to give marriage licenses anymore to any couple where both people are over the age of 55. Would that be constitutional?

CHIEF JUSTICE JOHN ROBERTS: If you tell a child that somebody has to be their friend, I suppose you can force the child to say, this is my friend, but it changes the definition of what it means to be a friend.

SOLICITOR GENERAL DONALD VERRILLI: The principal argument in 1967 ... was: Well, the social science is still uncertain about how biracial children will fare in this world, and so you ought to apply rational basis scrutiny and wait. And I think the Court recognized that there is a cost to waiting and that that has got to be part of the equal protection calculus.

JUSTICE ANTHONY KENNEDY: There are some 40,000 children in California...that live with same-sex parents, and they want their parents to have full recognition and full status. The voice of those children is important in this case, don’t you think?

JUSTICE STEPHEN BREYER: Let’s look at California. What precisely is the way in which allowing gay couples to marry would interfere with the vision of marriage as procreation of children that allowing sterile couples of different sexes to marry would not? I mean, there are lots of people who get married who can’t have children.

JUSTICE ANTONIN SCALIA: If you redefine marriage to include same-sex couples, you must -- you must permit adoption by same-sex couples, and there’s - there’s considerable disagreement among -- among sociologists as to what the consequences of raising a child in a -- in a single-sex family, whether that is  harmful to the child or not.

ATTORNEY TED OLSON: This is a measure that walls off the institution of marriage, which is not society’s right. It’s an individual right ... It’s a part of the right of privacy, association, liberty, and the pursuit of happiness.

ATTORNEY CHARLES COOPER: It is reasonable to be very concerned that redefining marriage ...as a genderless institution could well lead over time to harms to that institution and to the interests that society has always ... used that institution to address.

JUSTICE SAMUEL ALITO: You want us to step in and render a decision based on an assessment of the effects of this institution which is newer than cell phones or the Internet? I mean we -- we are not -- we do not have the ability to see the future.