“What we are practicing here is not voodoo,” said Katherine Mistretta, a family nurse practitioner who is one of the plaintiffs in the Montana lawsuit. “I think our justice system will see that there’s enough science to support this, that they will understand that this is appropriate care.”

The bill signed on Friday, Senate Bill 99, was just one of a slate of measures focused on gender identity that the Montana legislature has been advancing this month, including one that would define sex in binary terms and one that would bar public school students from changing their pronouns without parental permission.

For abortion rights groups, state constitutions are a critical part of a strategy to overturn bans that have cut off access to abortion in a wide swath of the country. Those documents provide much longer and more generous enumerations of rights than the United States Constitution, and history is full of examples of state courts using them to lead the way to establish broad rights — as well as to strike down restrictions on abortion. They offer a way around gerrymandered state legislatures that are pushing stricter laws.