The U.S. Supreme Court’s conservative justices late Wednesday refused to block Texas’ six-week ban on abortions nearly 24 hours after it went into effect.

In an unsigned order, from which Chief Justice John Roberts and the court’s liberal members dissented, the court’s majority said abortion providers challenging the law “have raised serious questions regarding the constitutionality of the Texas law,” but “their application also presents complex and novel antecedent procedural questions on which they have not carried their burden.”