The US Justice Department has filed a lawsuit against the state of Texas over a new law that bans nearly all abortions in the state, saying it is unconstitutional.
The state law, known as Texas Senate Bill 8, or SB8, took effect on September 1. It bans abortions once medical professionals can confirm the heartbeat of an embryo, unless there is a threat to the mother's life.
The cardiac activity is normally detected at around six weeks of pregnancy, before many women even realize they are pregnant.
US media have described the Texas state law as the strictest anti-abortion law. The law makes no exceptions for pregnancy resulting from rape or incest.
The Justice Department filed the lawsuit with a court in Texas on Thursday, seeking an immediate injunction to prohibit the law's enforcement.
Attorney General Merrick Garland said "The act is clearly unconstitutional under longstanding Supreme Court precedent." He added, "This kind of scheme to nullify the Constitution of the United States is one that all Americans -- whatever their politics or party -- should fear."
Texas Governor Greg Abbott, a Republican, defended the law. His spokesperson said in a statement that "the most precious freedom is life itself." The statement added, "We are confident that the courts will uphold and protect that right to life."
Abortion remains a deeply polarizing issue in the US.
The US Supreme Court, where conservative justices hold a majority, allowed the law to stand although women's rights activists and others were seeking an injunction.