Washington DC - President Joe Biden said Friday that the Equal Rights Amendment, designed to ensure equality before the law regardless of one's sex, is already part of the US Constitution – a view disputed by political opponents as well as the National Archives.

"In keeping with my oath and duty to Constitution and country, I affirm what I believe and what three-fourths of the states have ratified: the 28th Amendment is the law of the land," the outgoing president said in a statement.

While Biden's proclamation carries no legal weight, it is seen as a defiant gesture just three days before he cedes power to Republican Donald Trump, whose first-term Justice Department had suggested the amendment was a dead letter.

Congress adopted the ERA in 1972 as a measure to give constitutional backing to demands for equal treatment of men and women.

Politicians Alexandria Ocasio-Cortez attacks Democrats over transgender sports bill defections

For such an amendment to become US law requires ratification by three-quarters of the states, or 38 of the 50.

Conservative groups fiercely opposed the amendment, arguing that it would open the door to unisex toilets, same-sex marriage, and the conscription of women into the military, as well as make the ratification process move slowly.

Virginia became the 38th state to ratify the ERA in 2020 – nearly 40 years after a 1982 deadline originally set by Congress, and far too late to count, opponents say.

Biden said his argument, backed by the American Bar Association and "leading legal constitutional scholars," maintains that Virginia's ratification means "the Equal Rights Amendment has become part of our Constitution."

The formal inclusion of an amendment into the Constitution requires action by the US National Archives. But Archives director Colleen Shogan, citing court decisions affirming the original deadline, has refused to publish the amendment.

Biden does not intend to order her to do so, according to several media reports. Shogan was nominated to the position by Biden.

Biden's declaration could, however, give some clout to pro-ERA forces in a future court battle, especially because some legal experts have long held that the deadline lacks validity.

According to the New York Times, Biden would like to force his successor to publicly argue against the amendment – and thus against equal rights for women – if the matter reaches the courts.