Pro-choice protesters from NARAL stand outside Mitt Romney's hotel in Washington, D.C. last March. Getty Images Abortion is possibly the most divisive issue in the United States.

Pro-choice advocates argue that women should have total control over their own bodies. Anti-abortion advocates believe life begins at conception, so abortion is murder.

There's little (if any) common ground.

As it stands, the U.S. Supreme Court recognized a woman's right to abort a pregnancy in Roe v. Wade 40 years ago.

On a more fundamental level, Roe v. Wade didn't just allow women to legally obtain abortions. It affirmed the right of doctors to practice medicine without interference from the states, unless the state had a compelling interest.

Well, the definition of what constitutes a "compelling interest" seems to have expanded since Roe v. Wade. States all across the nation have enacted, or are in the process of enacting, many laws restricting access to abortions.

A Guttmacher Institute study found that 135 abortion restrictions were enacted at the state level in 2011 and 2012.

There have been quite a few attempts to limit abortion rights at the federal level, as well.

At the March for Life in Washington, D.C. on Friday, Jan. 25, John Boehner told the crowd "making abortion a relic of the past" is "one of our most fundamental goals this year."