In 2007, two women, Edith Windsor (plaintiff) and Thea Spyer, were legally married in Ontario, Canada. Windsor and Spyer returned to New York, which recognized the marriage. Two years later, Spyer died, leaving her estate to Windsor. Windsor claimed the federal estate-tax exemption for surviving spouses but was denied under the Defense of Marriage Act (DOMA), 1 U.S.C. § 7. The provision amends the definition of marriage to a “union between one man and one woman” and defines spouse as an opposite-sex husband or wife. Windsor paid the taxes and sued in federal court, challenging the constitutionality of the restriction. The Attorney General issued a letter notifying Congress that the Department of Justice (DoJ) would not defend DOMA’s constitutionality anymore, though it would continue to enforce the provision. The House of Representatives authorized the Bipartisan Legal Advisory Group (BLAG) to defend DOMA on its behalf. BLAG was granted permissive intervention. The district court held that the provision was unconstitutional and Windsor was entitled to a refund. The court of appeals affirmed on the basis of heightened scrutiny for classifications based on sexual orientation. The government and BLAG petitioned the United States Supreme Court for certiorari, which was granted.