WASHINGTON -- Mitt Romney artfully dodged a question about whether states have the right to ban birth control during Saturday's Republican presidential debate, calling the question "silly" and saying that states wouldn't want to do that anyway. But as governor of Massachusetts in 2005, Romney took a harder line on contraception, vetoing a widely supported bill that would make the morning-after pill available over the counter in that state and require hospitals to offer emergency contraception to rape victims.

His surprising veto did not stand. The Massachusetts state Senate voted unanimously to overrule it, and the state House voted 139-16 to do the same.

Romney tried to explain his controversial act by arguing in a Boston Globe op-ed that he did it in order to keep a campaign promise not to change Massachusetts' abortion laws. But the scientific community and longstanding federal policy agree that the morning-after pill cannot end a pregnancy once it has begun.

President Barack Obama's administration has also gone against scientific consensus on contraception. In December, Health and Human Services Secretary Kathleen Sebelius unexpectedly overruled the Food and Drug Administration's science-based recommendation that the Plan B morning-after pill be made available on pharmacy shelves; the FDA had concluded that over-the-counter availability was safe for women of all ages. Although Obama said he had no part in Sebelius' decision, women's health advocates, as well as members of the Congressional Pro Choice Caucus and the scientific community, expressed their strong disappointment with his administration for rejecting sound science on the issue of contraception.

"Secretary Sebelius used phrases like 'based on my review' and 'my conclusion,'" Francesca Grifo of the Union of Concerned Scientists said during a Friday meeting of the President's Council of Advisers on Science and Technology. "This is exactly the situation which scientific integrity policies are created to prevent: namely, a non-scientist political appointee overturning a decades-long process of scientific research and review both inside and outside of the FDA."

Even after Sebelius' decision, women 17 and older can still buy Plan B without a prescription. By contrast, Romney's veto of the contraception bill would have had harsher consequences: It would have maintained a prescription requirement for emergency contraception in Massachusetts and limited rape victims' access to it. The decision, along with Romney's scientifically misguided argument that emergency contraception pills can end a pregnancy, provides a preview of the kinds of health-related decisions he might make as president.

Romney's op-ed cited arguments from many anti-abortion groups including the Family Research Council, which more recently released a statement praising Sebelius' decision on the ground that "Plan B can act in a way that can destroy life by preventing implantation."

"Women of all ages have the right to know how this drug may act in their bodies and on their newly developing babies," Jeanne Monahan, director of Family Research Council's Center for Human Dignity, wrote in the statement.

But according to the nonpartisan American Congress of Gynecologists and Obstetricians, pregnancy begins at the moment the fertilized egg is implanted in the uterus. Unlike a medication abortion, emergency contraception has no effect on a developing embryo. And by requiring a prescription for the morning-after pill for those under age 17, medical experts say, the government is jeopardizing their ability to access the pill in time to actually prevent a pregnancy.

"Timing is critical," James N. Martin Jr., president of the American Congress of Gynecologists and Obstetricians, recently wrote. "[Emergency contraception] is most effective when taken within 72 hours after unprotected intercourse. This is why OTC access is so important. There's no need to wait for a doctors' appointment to get a prescription, or to have the prescription filled."

Romney's anti-contraception policies do not end with the morning-after pill. He has also pledged to eliminate the Title X family planning program, which provides affordable contraception and other basic medical care to millions of uninsured or low-income women in medically underserved communities across the country.

His spokeswoman did not respond to a request for comment.

Ted Miller, spokesman for NARAL Pro-Choice America, said that although Romney is often seen as a relatively moderate GOP candidate and once considered himself "pro-choice," he is still far to the right of Obama on issues affecting women's health and reproductive rights.

"As we said at the time, the Obama administration's decision on Plan B was a missed opportunity to further distinguish the president's record from those of candidates like Romney who have taken actions against birth control," Miller told HuffPost. "Perhaps Romney's plan to make it harder for women to access contraception is the reason he tried to play down the issue of birth control during Saturday's debate."

Earlier on HuffPost: