From the Washington Post:
The key to the brief is that it makes two arguments. The first is that it agrees with the ruling of a lower court — which found Prop 8 unconstitutional — that challenges to the constitutionality of such laws should require that they are subjected to “heightened scrutiny.” That means the court should hold their rationale for discriminating to an extremely high standard, and strike them down if they fail to have a credible justification. The brief does that here, in a reference to previous Supreme Court ruling in cases involving challenges to discriminatory laws:"[C]lassifications based on sexual orientation call for application of heightened scrutiny. Each of the four considerations identified by this Court supports that conclusion: (1) gay and lesbian people have suffered a significant history of discrimination in this country; (2) sexual orientation generally bears no relation to ability to perform or contribute to society; (3) discrimination against gay and lesbian people is based on an immutable or distinguishing characteristic that defines them as a group; and (4) notwithstanding certain progress, gay and lesbian people — as Proposition 8 itself underscores — are a minority group with limited power to protect themselves from adverse outcomes in the political process. [...]Because a classification based on sexual orientation calls for the application of heightened scrutiny, petitioners must establish that Proposition 8, at a minimum, is “substantially related to an important governmental objective.”The second key to the brief is that it argues that when you apply “heightened scrutiny” to Prop 8, it is found to violate the equal protection clause of the U.S. Constitution.What this means is that the government, while focusing its brief on Prop 8 itself, has, for all practical purposes, asked the Supreme Court to set a precedent that can be applied to all state laws banning gay marriage — the arguments that these laws must survive “heightened scrutiny,” and that they violate the Constitution.