A Texas law banning most abortions in the state took effect Wednesday, with the Supreme Court silent on an emergency appeal to put the law on hold.

If allowed to remain in force, the law would be the most far-reaching restriction on abortion rights in the United States since the high court’s landmark Roe v. Wade decision legalized abortion across the country in 1973.

The Texas law, signed by Republican Gov. Greg Abbott in May, prohibits abortions once a heartbeat can be detected in a fetus, usually around six weeks and before most women know they’re pregnant.

In a statement after the law took effect, President Joe Biden said it “blatantly violates the constitutional right established under Roe v. Wade and upheld as precedent for nearly half a century.” And he said the law “outrageously” gives private citizens the power “to bring lawsuits against anyone who they believe has helped another person get an abortion.”

In a phone call with reporters early Wednesday, Marc Hearron, a lawyer for the Center for Reproductive Rights, said that “as of now, most abortion is banned in Texas.” Hearron said his group and the abortion providers it represents were still hoping to hear from the Supreme Court.