Judges on the U.S. Court of Appeals for the Ninth Circuit weighed the constitutionality of Idaho’s law that makes it illegal for an adult to help a girl obtain an abortion across state lines, spending much of a hearing Tuesday trying to pinpoint precisely what conduct the statute prohibits.

Idado’s so-called abortion travel ban, which went into effect last May, criminalizes “recruiting, harboring, or transporting” a pregnant minor to access a legal abortion if the adult has the intent to conceal the abortion from a parent or guardian.