On Monday, the Supreme Court ensured that an Arizona law to ban abortions after 20 weeks would not take effect. The high court declined to review the law after a federal appeals court ruled it unconstitutional, thereby making the ban unenforceable.

In its 1973 Roe v. Wade decision, the Supreme Court ruled that a woman has a constitutional right to have an abortion until such time as the fetus is viable outside of the womb, about 24 weeks at the earliest. In recent years, a growing number of states have enacted strict abortion legislation that violates the Supreme Court’s ruling in Roe.

In April 2012, Arizona Governor Jan Brewer (R) signed the restrictive abortion bill into law. HB 2036 was particularly strict because it redefined gestation in a way that could have banned abortion as early as 18 weeks. At the time, it was the most restrictive abortion ban in the nation.

In November 2012, a federal appeals court examined the law after three abortion providers challenged the law in court, along with the American Civil Liberties Union. Judge Andrew Kleinfeld, a panel member and appointee of former President George W. Bush expressed concern that the law would not give women the opportunity to abort a fetus with severe birth defects, which may not be apparent before 20 weeks.

Arizona’s then-solicitor general, David Cole said “That’s the woman’s problem. She should have made that decision earlier.” In July 2012, the panel blocked the law until it could fully consider the case. Last year, the federal appeals court ruled that the law was unconstitutional. Now the Supreme Court has indicated that it is not interested in taking up a challenge to that ruling.

According to the Guttmacher Institute, several states have banned abortion at 20 weeks post-fertilization, including Alabama, Arkansas, Indiana, Louisiana, Nebraska, North Dakota, Oklahoma, and Texas. Many legislators have enacted these laws based on incomplete and disputed scientific research that states that fetuses can feel pain at 20 weeks. According to The New York Times,

Dr. Anne Davis, consulting medical director for Physicians for Reproductive Health, who performs abortions until 24 weeks, said publicity about the laws had prompted patients to ask about fetal pain. She tells them that ‘the best evidence is the fetuses are not feeling pain until pretty much into the third trimester.’

Some scientists say if fetuses feel pain, childbirth would seem to be particularly painful. Yet fetal-pain law supporters do not advocate fetal anesthesia or painkillers then.

One scientist whose work on fetal pain is frequently cited by anti-choice advocates and was referenced during Congress’s debate over a potential 20-week nationwide ban on abortions this past June, is Dr. Kanwaljeet Anand.  He recently told The Times that his research was never intended to support anti-abortion efforts. Abortion decisions should be made by women and their doctors, case by case, he said.

The “issue of fetal pain does not have much relevance for abortion, since most abortions are performed before the fetus is capable of experiencing pain,” Anand said. And, in reality, only 1.5 percent of abortions in the United States occur at 21 weeks or later. An overwhelming majority, 61.8 percent, occur at 9 weeks or earlier.

The Supreme Court decision not to challenge the federal appeals court’s ruling on Arizona’s restrictive abortion ban is a small victory for women’s rights advocates. However, the legislative war on women has been escalating in recent years. In 2013, 39 states enacted 141 provision related to women’s reproductive health and rights, half of which aimed to restrict access to women’s constitutional right to have an abortion.

US lawmakers enacted more abortion restrictions during 2011, 2012, and 2013 than during the previous decade (2001 to 2010), the Guttmacher Institute reports.

Alisha is a writer and researcher with Ring of Fire. You can follow her on Twitter @childoftheearth.