A so-called "emergency contraceptive" that has been central to recent court battles due to its mandated coverage by the Obama administration works most often by causing an abortion, according to a review of medical data published this month in the journal The Linacre Quarterly.

After studying the most recent scientific and medical evidence on levonorgestrel emergency contraception, which goes by the brand name Plan B, the researchers concluded that the women who take it do not get pregnant because it "quite often" causes an abortion if taken before ovulation.

Plan B was first approved for use by the Food and Drug Administration in 1999. After passage of the Affordable Care Act, or "Obamacare," the Health and Human Services Administration required most employers to cover Plan B and other FDA-approved emergency contraceptives in their employee's health insurance plans.

This "birth control mandate" led to numerous court battles involving religious groups and businesses, some of whom only objected to coverage of certain emergency contraceptives due to their potential to behave like an abortifacient drug.

In one of those cases involving Hobby Lobby, a craft store chain owned by an Evangelical family, the Supreme Court ruled last Summer that closely-held companies with a religious objection do not have to cover the drug.

The cases involving religious nonprofits, such as Christian colleges and social service groups, have continued. On Wednesday, the U.S. Court of Appeals for the Eleventh Circuit heard oral arguments in a challenge to the mandate by EWTN Global Catholic Network, a television and radio ministry founded by a nun.

During the cases that only involved coverage of emergency contraceptives, some supporters have claimed that the science indisputably shows that Plan B never causes an abortion, even though scientists continue to debate how the pill actually works.

Plan B is to prevent a pregnancy after having sex with no other form of birth control. (It is not the same as RU-486, which both sides of the abortion debate acknowledge is an abortifacient.)

The authors address eight different claims regarding how Plan B is presumed to work. Examining the most recent research on Plan B, the authors conclude that those claims have no basis for support.

The authors also note that some claim Plan B does not cause an abortion by first redefining the term "abortion." An abortion, they claim, can only occur after implantation, rather than at conception, when life begins.

In 2012, when there was much debate over Plan B and Obamacare, for instance, the International Federation of Gynecology and Obstetrics released a statement saying that Plan B does not inhibit implantation. Some liberal news sites reported on that statement under headlines like, "Abortion Qualms on Morning-After Pill May Be Unfounded," and "Morning-After Pills Don't Cause Abortion, Studies Say."

Plus, at the time of this publication, the WebMD page for Plan B states that the drug does not cause an abortion, but then redefines abortion as stopping "development of a fetus once the fertilized egg implants in the uterus."

The Linacre Quarterly is the official journal of the Catholic Medical Association and explores ethical issues with a medical dimension. The report was written to guide Catholic hospitals on the use of Plan B for rape victims.

The effect of Plan B depends upon the menstrual cycle of the patient, they concluded. If Plan B is given within two days before ovulation, Plan B "has significant potential to work via the death of the embryo."

If Plan B is taken after ovulation, it could have opposite the intended effect. Plan B "in the postovulatory period may be increasing a woman's risk of becoming clinically pregnant."

Based upon these findings, the authors conclude that current Catholic hospital rape protocols "appear to be faulty and should be revised."

"Since the most recent medical data clearly note that [Plan B] does not effectively stop ovulation and has high potential to work via abortion when given prior to ovulation, these protocols would no longer be in compliance with Catholic teaching," they wrote.

Judie Brown, president of American Life League, agreed with the report's conclusions.

"Catholic bishops have been assured, by Plan B proponents, that the drug does not cause an abortion," she said. "We now know this is not true. There is a grave risk that preborn human lives are being killed by Plan B, and Catholic hospitals need to immediately halt dispensing these drugs and review their policies."

The authors of the report are Chris Kahlenborn of The Polycarp Research Institute, Rebecca Peck of the Florida State University College of Medicine, and Walter Severs of the College of Medicine at Penn State University.