In Congress and state legislatures across the country, right-wing politicians are pushing hard to construct new barriers to women exercising the constitutional right to have an abortion.

Earlier this month the U.S. House passed a bill banning abortions after 20 weeks of pregnancy, and GOP legislators in Wisconsin are staging a parallel attack. They introduced a similar 20-week ban, which Gov. Scott Walker has indicated he would sign, and have scheduled a hearing on the bill for next week. PFAW supporters in Wisconsin will be out in force to demonstrate their commitment to protecting this core right.

A couple of important points about 20-week bans: first, they are plainly unconstitutional. One of the main holdings of the 1973 Roe v. Wade decision was a woman’s right to an abortion before the fetus becomes viable – that is, the point when a fetus could survive outside the uterus. As Imani Gandy writes at RH Reality Check:

In the past 40 years, the Court has never wavered from the fetal viability benchmark…Courts have consistently smacked down legislative attempts to ban abortions at 20 weeks. But states are undeterred by such pedestrian concerns as constitutionality.

Pushing these bans are a deliberate effort to prompt a challenge to the Roe decision, which anti-choice groups believe they can win.

Second, the overwhelming majority of abortions (close to 99 percent) happen before 21 weeks. Those that happen after that are often because of a complicated situation – such as the discovery of a severe fetal abnormality – and the path forward should be determined by a woman and her doctor, not by politicians looking to score points with their base.

Finally, and perhaps most importantly, these bans are part of an anti-choice agenda with a much broader goal: banning abortions across the board. From mandatory waiting period laws to “personhood” efforts which would give embryos full legal rights from the moment of conception, the anti-choice movement is playing the long game and slowly “chipping away at choice.”

When legislators try to insert themselves into decisions that should be made by women and their health care providers, it’s more than a political ploy. It’s a real threat to every woman’s health and autonomy.