A group of doctors and women’s rights advocates challenged Arizona’s new abortion limits in a federal lawsuit on Thursday, asserting that they violate the Constitution and pose a threat to women’s health.
The law, set to take effect on Aug. 2, prohibits abortions once 20 weeks have passed since a woman’s last missed period, which is about 18 weeks after fertilization. This is the earliest deadline set by any state and is weeks earlier than the threshold set by the Supreme Court.
In Roe v. Wade and related decisions, the court ruled that women have a right to abortion until the fetus is viable outside the womb, often about 24 weeks, and that any ban on later abortions must allow exceptions to protect the life and health of the mother.
The Arizona law allows medical exceptions only in extreme emergencies, when delay would cause the mother’s death or the ‘‘irreversible impairment of a major bodily function.’’
Thursday’s lawsuit, filed in US District Court in Phoenix, might bring the first major test of pre-viability time limits that have recently been adopted in eight other states.
Legislators in these states have cited evidence — disputed by major medical societies — that the developing fetus can feel pain.
But the Arizona law sets a limit two weeks earlier than the ‘‘fetal pain’’ laws passed since 2010 in Alabama, Georgia, Idaho, Indiana, Kansas, Louisiana, Nebraska, and Oklahoma, said Elizabeth Nash, state issues manager with the Guttmacher Institute, a research group in Washington that supports abortion rights.
“This is the most extreme example yet of these early-limit laws,’’ said Nancy Northup, president of the Center for Reproductive Rights which brought the lawsuit with the American Civil Liberties Union and three doctors in Arizona.
Cathi Herrod, president of the Center for Arizona Policy, a conservative Christian group that helped write the law, said it was needed to protect the health and safety of women and protect ‘‘preborn children.’’