NASHVILLE (AP) — The Tennessee attorney general's office says it would defend an amended abortion bill in court if it becomes law, despite previously calling the legislation's key restrictions "constitutionally suspect."

The bill would ban abortions after 20 weeks if doctors determine the fetus is viable through required testing. The ban wouldn't apply in medical emergencies or if the mother faces risks of death or serious damage to a major bodily function.

Attorney General Herbert Slatery had initially questioned the bill's constitutionality in an opinion last month. His spokesman, Harlow Sumerford, has since said "the law to some degree is unsettled" surrounding the proposal. The opinion "points out that the statute might not necessarily be immune to legal challenges," Sumerford said.

Anti-abortion advocates contend they have since amended the bill and addressed issues of constitutionality. The American College of Obstetricians and Gynecologists' state chapter still worries doctors could be at risk of facing criminal charges for simply using their best medical judgment, a main issue raised in the attorney general's opinion.

The bill by Rep. Matthew Hill, a Jonesborough Republican, and Sen. Joey Hensley, a Republican from Hohenwald, could receive a Senate floor vote this week. It's in a House committee Tuesday.

Slatery's opinion questioned whether multiple aspects of the bill would be unconstitutional.

Without proving the doctor has "guilty knowledge" or recklessness, Slatery wrote that "such statutes impermissibly subject a physician to criminal liability even though he was acting in good faith in determining whether a medical emergency or medical necessity exists."

For doctors, violating the post-viability ban would be a Class C felony. Violating the viability testing requirement would be a Class A misdemeanor.

Paul Linton, an attorney with Tennessee Right to Life, said the bill's amendment ensures that "there's no possibility that a doctor could be convicted if he's acting in good faith."

The American College of Obstetricians and Gynecologists remained concerned. Beth Berry, lobbying for the group's state chapter, said there is no definitive test for viability and disagreements could arise, leaving doctors open to prosecution and lawsuits.

"Experts can disagree whether it was a medical necessity. Experts can disagree whether it was an emergency," Berry said. "And to have physicians subject to criminal and civil liability when they can't even understand what the definitive law is, it's a major concern for doctors."

Slatery's opinion also said the bill could be unconstitutional because it doesn't account for severe mental and emotional harm when considering if an abortion is medically necessary.

The bill specifies that abortions would still be outlawed if a woman has a mental health state, diagnosed or otherwise, that would lead her to commit suicide or irreversibly harm herself if she doesn't have the abortion.

Anti-abortion advocates disagreed, and that part of the bill remains intact.

Linton said he believes U.S. Supreme Court precedent allows limiting post-viability abortion to women who have serious physical health reasons.

Gov. Bill Haslam's office is still reviewing the amended bill, according to Haslam spokeswoman Jennifer Donnals.