The governor and attorney general of Nevada are withdrawing their defense of the state's ban on same-sex marriage, marking the third time since last summer that state law-enforcement officials have publicly disavowed laws limiting marriage to one man and one woman.

In court papers filed late Monday with the 9th U.S. Circuit Court of Appeals, the Nevada Attorney General, Catherine Cortez Masto, said that neither she nor other state officials, including Gov. Brian Sandoval, a Republican, would continue to defend the state's same-sex...