Omaha, Neb. ? Bolstered by the passage of unique abortion restrictions in his home state of Nebraska, U.S. Sen. Mike Johanns is pushing for a new federal discussion of the notion of fetal pain.

Although doctors are at odds about when during development a fetus can feel pain, it’s an issue that could change the way abortions are regulated in the United States.

The Nebraska law that takes effect Friday bans abortions after 20 weeks of pregnancy based on the idea of fetal pain, a departure from the standard of viability — when the fetus could survive outside the womb, generally considered to be between 22 and 24 weeks — established by the 1973 landmark ruling in Roe v. Wade.

Legislation recently reintroduced by Johanns doesn’t go that far. It would require women seeking abortions after 20 weeks to be told the fetus could feel pain and allow them to request anesthesia for the fetus. The measure was first proposed by Kansas Sen. Sam Brownback in 2004 and has been reintroduced every year since.

“How does anybody — pro-life or pro-choice — oppose this?” asked Johanns, a Republican. “If the baby feels pain … then it is an issue of human compassion.”

Critics say the proposal is based on false science.

Vicki Saporta, president of the National Abortion Federation, a group representing North American abortion providers, said such legislation “keeps resurfacing but it has not moved forward — and should not move forward — since there is no credible scientific evidence to support the bill.”

Testimony at a 2005 congressional hearing — with some doctors saying fetuses could feel pain and others saying they could not — suggests the medical community hasn’t reached consensus on when during development a fetus can feel fetal pain. That testimony was cited in the Nebraska Legislature as it debated the bill.

The American College of Obstetricians and Gynecologists says it knows of no legitimate evidence showing a fetus can ever experience pain.