Well, in the United States there is State law and Federal law. Roe vs. Wade was fought/won on the federal level (through U.S. Supreme Court). Generally, and this gets confusing even to American citizens, but state law supercedes within it's own state and is still free to enact its own laws. South Dakota state law appears to be attempting to challenge the federal ruling of Roe vs. wade by first passing anti-abortion legislation in its own state. Which from a liberalist perspective, can pose a serious threat to women's freedom of choice nationally. It's possible that South Dakota may be hoping to get women from their state to challenge the law on the federal level with a conservative bench intact? Then, the possibility of reversing the Roe v. Wade decision is more probable.