In a filing made on Friday, the Obama Administration urged the Supreme Court to strike down the Defense of Marriage Act, saying courts considering laws targeting gay people should do so with extra scrutiny, and calling it unconstitutional.

Solicitor General Donald Verrilli argued that Section 3 of DOMA, which defines “spouse” and “marriage” under federal law as exclusively between one man and one woman, is unconstitutional.

Obama’s Administration wrote: “Section 3 of DOMA violates the fundamental constitutional guarantee of equal protection. The law denies to tens of thousands of same-sex couples who are legally married under state law an array of important federal benefits that are available to legally married opposite-sex couples. Because this discrimination cannot be justified as substantially furthering any important governmental interest, Section 3 is unconstitutional.”

The filing goes on to address the question of what would be to become of DOMA if the court does not agree that a heightened level of scrutiny applies. It reads: “If the Court … applies rational-basis review, the government has previously defended Section 3 under rational-basis review, and does not challenge the constitutionality of Section 3 under that highly deferential standard.”

The administration adds that the Supreme Court could consider what has been referred to as a “more searching form” of the rational-basis review.

“To the extent sexual orientation may be considered to fall short in some dimension [to have heightened scrutiny applied], the history of discrimination and the absence of relation to one’s capabilities associated with this particular classification would uniquely qualify it for scrutiny under an approach that calls for a measure of added focus to guard against giving effect to a desire to harm an ‘unpopular group.’

“[G]ay and lesbian people are a minority group with limited political power. Although some of the harshest and most overt forms of discrimination against gay and lesbian people have receded, that progress has hardly been uniform (either temporally or geographically), and has in significant respects been the result of judicial enforcement of the Constitution, not political action.”

The administration also addresses the argument put forward by House Republicans through the Bipartisan Legal Advisory Group (BLAG), that this is not an issue for the courts to decide, saying that, given the discrimination which results from the law, and the clash with the US Constitution, it should be invalidated.

“BLAG makes an appeal to this Court to allow the democratic process to run its course. That approach would be very well taken in most circumstances. This is, however, the rare case in which deference to the democratic process must give way to the fundamental constitutional command of equal treatment under law. Section 3 of DOMA targets the many gay and lesbian people legally married under state law for a harsh form of discrimination that bears no relation to their ability to contribute to society. It is abundantly clear that this discrimination does not substantially advance an interest in protecting marriage, or any other important interest. The statute simply cannot be reconciled with the Fifth Amendment’s guarantee of equal protection. The Constitution therefore requires that Section 3 be invalidated.”

The other case addressing equal marriage at the Supreme Court could also be addressed by the administration. The deadline is 28 February for it to file an amicus curiae brief, to announce its views on the challenge to California’s Proposition 8.

The Supreme Court is due on 26 March to take up the case of whether to overturn Proposition 8, which in 2008 added a clause to the Californian constitution stating that marriage could only be recognised by the state if it were between a man and a woman, causing widespread controversy.

Earlier this week, one of the key players in President Obama’s re-election campaign joined efforts in the US state of Ohio to repeal its ban on equal marriage.