SAN FRANCISCO — The U.S. Supreme Court may be on the way to banning some abortions before fetuses reach viability. But it hasn’t gotten there yet — even under its most restrictive recent ruling — and therefore an Arizona law banning most abortions after 20 weeks’ gestation is unconstitutional, a Ninth Circuit panel strongly hinted Monday.

“Lower courts should not act in anticipation of where the Supreme Court might go,” attorney Janet Crepps of the Center for Reproductive Rights argued, and Judge Marsha Berzon was quick to agree.