Idaho became the first U.S. state to enact a law modeled after the recent legislation passed in Texas that bans abortions after six weeks, before many women know they’re pregnant.

The new law also allows the father, grandparents, siblings, uncles or aunts of the fetus to sue a medical provider who performs the procedure.

The bill passed the state House of Representatives and Senate earlier this month and was signed by Republican Gov. Brad Little on Wednesday.

“I stand in solidarity with all Idahoans who seek to protect the lives of preborn babies,” Little wrote in a letter to Lt. Gov. Janice McGeachin, president of the state Senate.

However, he expressed worries about whether the law is constitutional and whether it would stand challenges in court.

“While I support the pro-life policy in this legislation, I fear the novel civil enforcement mechanism will, in short order, be proven both unconstitutional and unwise,” Little wrote.

The law will go into effect, but opponents said they are already preparing to challenge the bill.

One criticism is that prenatal scans often detect cardiac activity very early in pregnancies, but they’re not heartbeats. They’re signs of what will eventually become a heart.

Another criticism is that family members can sue for a minimum of $20,000 within four years of an abortion. While a rapist wouldn’t be allowed to sue, their family members could.

Kim Clark, senior attorney at Legal Voice — a non-profit organization advocating for the legal rights of women, girls and LGBTQ people in the Northwest — said this could lead to women in abusive relationships being further harassed by their partners.

“This essentially makes the state complicit in intimate partner violence,” Clark told ABC News in an interview last week. “Allowing a member of the person’s family to bring a claim, that could include an abuser where the survivor hasn’t reported the assault.”

Although the Idaho law is the first in the nation to be modeled after the Texas law, there are a few differences.

Both allow for exceptions in the case of a medical emergency, but the Texas law does not allow for exceptions in cases of rape or incest. In contrast, the Idaho bill does allow for such exceptions.

However, women who want an abortion under those exceptions in Idaho are required to file a police report and show it to the medical provider before the abortion.

Another difference between the two pieces of legislation is that the Idaho bill only allows for certain family members of the fetus to sue the medical provider who performed the abortion, but the Texas law allows almost any private citizen to sue any Texas doctor who performs an abortion, intends to perform an abortion or helps a woman receive an abortion.