Arkansas Gov. Mike Beebe (D) vetoed on Tuesday a bill that would ban all abortions after 20-weeks of pregnancy, calling it "unconstitutional" and potentially very costly for the state.

H.B. 1037, The Pain-Capable Unborn Child Protection Act (PDF), would have banned abortions even before a fetus becomes potentially viable outside the womb, which Beebe noted runs afoul of the Supreme Court's ruling in Roe v. Wade setting viability between 24-28 weeks.

Though the bill was originally passed by the state House of Representatives without exceptions, the final bill contained exceptions for the life and health of the woman, as well as an exception for a pregnancy resulting from rape and incest. However, a study by Ibis Reproductive Health found that exceptions for federal funding allowed under the Hyde Amendment often go unfunded.

"[B]ecause it would impose a ban on a woman’s right to choose an elective, nontherapeutic abortion before viability, House Bill 1037, if it became law, would squarely contradict Supreme Court precedent," he wrote in a veto letter. "When I was sworn in as Governor I took an oath to preserve, protect, and defend both the Arkansas Constitution and the Constitution of the United States. I take that oath seriously."

He added that adopting unconstitutional laws can be "very costly to the taxpayers," even if anti-abortion attorneys argue on the state's behalf for free. "Lawsuits challenging unconstitutional laws also result in the losing party - in this case, the State - having to pay the costs and attorneys’ fees incurred by the litigants who successfully challenge the law," Beebe explained. "Those costs and fees can be significant."

Despite the veto, Republicans in the Arkansas legislature have the votes to override the governor's objection, requiring only a simple majority. The Senate Public Health, Welfare and Labor Committee also considered on Wednesday the Arkansas Human Heartbeat Protection Act (PDF), which seeks to ban abortions after 12 weeks of pregnancy, or as soon as a fetus's heartbeat can be detected.