Mississippi Gov. Phil Bryant (R) signed into law on Wednesday a bill that will ban abortion 20 weeks after a woman’s last menstrual period, or after 18 weeks’ gestation.

Twelve other states have passed 20-week abortion bans since 2010, relying on medically disputed claims that fetuses can feel pain at that age. But Mississippi’s HB 1400, while popularly known as a “20-week ban,” will actually outlaw abortion two weeks earlier than the 20-week bans in those other states.

The only other recent “20-week ban” that outlawed the procedure so early was Arizona’s, and that was blocked by courts because it unconstitutionally restricted abortion pre-viability. A fetus is generally considered viable around 24 weeks.

In its original form, HB 1400 did ban abortion at 20 weeks “post-conception,” which is similar to the language in other states and equates to 22 weeks after a woman’s last menstrual period. But the senate amended the bill to push back the cutoff date.

Whether at 18 or 20 weeks, however, these bans contradict Supreme Court rulings that abortion cannot be banned before a fetus is viable. Three 20-week bans, including Arizona’s, have already been blocked by courts for this reason, and West Virginia Gov. Earl Ray Tomblin (D) cited legal concerns when he recently vetoed a 20-week ban in his state.

Mississippi’s bill contains no exceptions for rape or incest, and only a limited exception for severe health issues or fatal abnormalities in the fetus.

Advocates say that legislators are wasting time passing unconstitutional bills that limit women’s health, especially in a state with such poor health outcomes for women as Mississippi. “With the women and families of their state facing extreme poverty, unacceptable rates of maternal mortality, and skyrocketing teen pregnancy, Mississippi’s elected officials have more than enough real work to do to bolster women’s well-being in their state,” said Nancy Northup, president and CEO of the Center for Reproductive Rights, in a statement.

Mississippi has one remaining abortion clinic, which only performs abortion until 16 weeks of pregnancy, and which has been fighting in court to stay open since state legislators passed a law in 2012 intended to close it.