Idaho Gov. Brad Little signed a bill into law on Wednesday that makes it illegal for an adult to help a minor get an abortion across state lines without parental consent.
The new law is the first of its kind in the United States and comes less than a year after Idaho banned nearly all abortions.
"With the U.S. Supreme Court's reversal of Roe vs. Wade last summer, the right and duty to establish legal policy on abortion was finally returned to our state democratic process," Little, a Republican, wrote in a letter to Idaho lawmakers on Wednesday, announcing he had signed the legislation.
The text of House Bill 242, which was first introduced to the Idaho Legislature in February, lays out a new crime of "abortion trafficking," in which an adult helps a pregnant, unemancipated minor obtain an abortion or abortion pills "by recruiting, harboring or transporting" them without the consent of their parent or guardian. Anyone who is found guilty of committing the crime will face two to five years in prison and could also be sued by the minor's parent or guardian. A parent or guardian who raped their child will not be allowed to sue.
The legislation allows an affirmative defense to prosecution -- an opportunity for a defendant to present evidence in court that could negate liability -- if "a parent or guardian of the pregnant minor consented to trafficking of the minor," unless the abortion provider was located in another state.
In his letter, Little clarified that the new law "does not criminalize, preclude or otherwise impair interstate travel, nor does it limit an adult woman from obtaining an abortion in another state."
"Rather, the 'abortion trafficking' provision in the bill seeks only to prevent unemancipated minor girls from being taken across state lines for an abortion without the knowledge and consent of her parent or guardian," he wrote.
Planned Parenthood Alliance Advocates West, a nonprofit advocating for reproductive rights in the states of Hawaii, Idaho and Washington, took to Twitter on Wednesday to vow to challenge Idaho's new law in court.
"Yet again, Idaho's governor disregarded constituents and signed HB 242 into law, creating the nation's first crime of so-called 'abortion trafficking,'" the group tweeted. "This legislation is despicable, and we’re going to do everything in our power to stop it."
Two weeks ago, Idaho became the first U.S. state to enact a law modeled after recent legislation passed in Texas that bans abortions after six weeks, before many women know they are pregnant. The Idaho law allows for exceptions in the case of rape, incest or a medical emergency, but women are required to file a police report and show it to the medical provider before the abortion. The legislation also allows the father, grandparents, siblings, uncles or aunts of the fetus to sue a medical provider who performs the procedure.
ABC News' Mary Kekatos contributed to this report.