Not long after the Supreme Court overturned Roe v. Wade, commentators warned that another right might unexpectedly be in danger: the right to travel. Republicans in Missouri proposed a law that would have allowed people to sue anyone who helped a resident travel out of state to end a pregnancy. Missouri’s bill didn’t pass, but it seemed to signal a new strategy—one that Idaho has now taken up. Idaho’s new “abortion trafficking” bill, passed earlier this month, criminalizes helping a pregnant minor travel to get an abortion or obtain abortion pills out of state without parental consent, and creates a right to sue doctors who perform abortions for those minors, even if those doctors live and work in a state where abortion is legal.

But in fact this is an old strategy, one that helped anti-abortion groups revoke the right to abortion. The movement learned a key lesson from the decades-long struggle to undo Roe: It’s easiest to start with minors.

Part of the reason is constitutional. In the 1970s, when states began introducing laws requiring parental consent or notification before minors got an abortion, state legislators knew that children didn’t always have the same constitutional rights as adults. States could insist, quite plausibly under the Constitution and other parts of American law, that minors sometimes need to be protected from the consequences of their own decisions in ways that adults do not.

There was a political reason for starting with minors too. Parental-involvement laws have always enjoyed broad public support—including from some Americans who support abortion rights. In the 1980s and ’90s, when these laws were spreading across the country, many who supported parental-involvement laws viewed them as almost unrelated to any attack on abortion: They were simply commonsense protections of parental authority.

For the anti-abortion movement, the end goal, of course, was not modest limitations on the freedom of minors. The more the Court believed that restrictions were acceptable for minors, abortion opponents hoped, the more the justices may come to see abortion as something that was unnecessary or even dangerous for adults too—and the more the Court may be willing to uphold restrictions that affected everyone. In turn, the more restrictions the Court upheld, the more legal conflicts could arise in the lower courts, and the more anti-abortion groups could argue that a right to choose was unworkable and incoherent. Additionally, limiting minors’ rights could set a political precedent, reinforcing the idea that at least some abortion restrictions were worth having.

Idaho’s law draws on the same incrementalist strategy. Conservative lawmakers might have hesitated to limit travel for abortion when roughly 70 percent of Americans, and a majority of Republicans, oppose laws banning the practice. And travel bans—including laws seeking to criminalize the behavior of doctors or others helping out-of-state abortion seekers who reached blue states—might fail in court. The Supreme Court has recognized protection for the right to travel between states since the early 19th century. In a series of decisions issued from the 1960s to the 1990s, the Court struck down laws that required Americans to live in a state for a certain amount of time before collecting welfare benefits. By any definition, the right to travel is “deeply rooted in the Nation’s history and tradition”—the test the Court set out in Dobbs v. Jackson Women’s Health Organization, the decision that reversed Roe—and no one could easily argue that the right to travel is a fiction invented by judicial activists, as Republicans once said of the right to an abortion. In his concurring Dobbs opinion, Justice Brett Kavanaugh reasoned that any law banning travel for abortion would obviously be unconstitutional.