London (CNSNews.com) - A pro-life group has launched a legal challenge in Britain's High Court to stop over-the-counter sales of the emergency contraceptive Levonelle, more commonly known as the morning-after pill.

The Society for the Protection of Unborn Children (SPUC) argued Tuesday that the pill is really a method of abortion and should be subject to U.K. abortion law, specifically the 1861 Offences Against the Person Act, which prohibits the distribution of substances that cause miscarriages.

The group said Levonelle stops an already-formed embryo from implanting in the lining of a woman's uterus. The pill has been available without a prescription from British drug stores for over a year, provided women requesting the drug answer a series of health questions.

Last year, the SPUC successfully applied for the right to challenge the government's position on the pill in court. In ruling on the case, the High Court will be asked to clarify the moment when a pregnancy begins under U.K. law.

The SPUC has consistently charged that Levonelle induces abortion, and the group has clashed with the U.K.'s Advertising Standards Authority over advertisements making that claim.

SPUC general secretary Paul Tully said that the group is concerned about the rising use of the morning-after pill in Britain.

"Even though there has been a five-fold increase in the use of the pill throughout the 1990s, the teenage pregnancy rate has also risen over the last decade," he said by phone Tuesday. "The government's policy is not working."

British pro-life and family planning groups were watching the case closely Tuesday. The Life organization expressed support for the SPUC's "brave initiative."

"It is enormously important that the lie about what women are doing to their bodies when they take these so-called 'contraceptive' pills should be squashed once and for all," said Life Trustee Nuala Scarisbrick. "(The pill's) chief purpose is not to stop a new life beginning but to destroy a life begun."

"The question now is, will the High Court judge have the courage to uncover the truth?" Scarisbrick said.

Family planning campaigners are worried that the decision could also affect the legality of other methods of birth control. Anne Furedi of the British Pregnancy Advisory Service (BPAS) said a decision in favor of the SPUC was "untenable."

"Such a ruling would set a precedent that all methods of contraception that might affect a fertilized egg would be methods of abortion," she said. "It's difficult to see how this could work in a modern, civilized society."

Furedi said the BPAS would advocate swift government action if the judges ruled in favor of the pro-life advocates.

"We would like to be confident that the High Court would reject the application, but the problem with judicial review cases is that sometimes they can result in maverick decisions," she said.

The spokeswoman called the case a publicity stunt on behalf of the SPUC.

"It's really a piece of cynical mischief-making on their behalf, rather than an honest attempt to positively influence the law," she said.

Tully, the SPUC general secretary, acknowledged that the group had little chance of overturning current law, but blamed the government and the Department of Health's intractable position.

"They have very little respect for the principals at stake," Tully said, noting that the government was prepared to introduce emergency legislation if the decision went in the SPUC's favor. "We're facing a government prepared to abuse their own power."

Tully said he welcomed the possibility that a ruling for his organization could spark a larger debate about birth control methods.

"The scope of the action is limited to the morning after pill ... (however) the case could have larger implications by forcing people to recognize the methods by which certain birth control devices work," he said. "The argument from the other side seems to be that they want to keep their heads in the sand."