Attorney General J.B. Van Hollen made his arguments in a brief filed with the 7th U.S. Circuit Court of Appeals in Chicago. Van Hollen is appealing a federal judge's June decision declaring Wisconsin's ban on gay marriage unconstitutional. The case has been combined with a similar one from Indiana.
U.S. District Judge Barbara Crabb had determined that the ban violated gay couples' equal protection and due process rights.
But Van Hollen said in his brief that the due process clause in the U.S. Constitution doesn't require states to grant rights but only bars them from depriving citizens of fundamental rights. Crabb's decision amounted to the creation of a new right of gay marriage, and letting it stand would greatly expand federal authority into an area traditionally controlled by states, he said.
Van Hollen compared gay marriage to abortion.
"Although the constitutional right of privacy protects a woman's right to obtain an abortion and precludes government from prohibiting or punishing her exercise of that right, there is no corresponding obligation on government to affirmatively endorse or support her exercise of the abortion right," he wrote.
Van Hollen also said sexual orientation has not been declared a "suspect class" subject to heightened protection like gender or race, and therefore doesn't deserve the same kind of deference in equal protection claims.
More than 500 same-sex couples married in Wisconsin in the week between Crabb's decision and her order putting marriages on hold while Van Hollen appeals.
Van Hollen did not argue against same-sex marriage in his brief. He said the federal Defense of Marriage Act had stepped on the right of states to recognize same-sex marriages if they wished, and in overturning it last year, the U.S. Supreme Court recognized states' authority to set standards for marriage.
But Van Hollen also noted that Wisconsin has historically defined marriage as between a man and a woman, and voters supported that in a 2006 amendment to the state constitution. He argued that the federal government should defer to states on the issue.
The attorney general submitted his brief on the same day that Marquette Law School released poll results showing 56 percent of Wisconsin voters support repealing the state's ban on gay marriages. The poll of 804 registered voters done between July 17 and Sunday had a margin of error of plus or minus 3.5 percentage points.