From both sides, attorneys agree that the laws represent an unprecedented frontal assault on the Supreme Court's 1973 Roe v. Wade decision that established a nationwide right to abortion.
The Arkansas law would ban most abortions from the 12th week of pregnancy onward. North Dakota's law would ban abortions as early as six weeks into a pregnancy, when a fetal heartbeat can first be detected.
Abortion-rights advocates will challenge both measures, contending they violate the Roe ruling that legalized abortion until a fetus could survive outside the womb. A fetus is generally considered viable at 22 to 24 weeks.