Boston ? When a pregnant woman told a pharmacist that she was unhappy with her obstetrics care, authorities say, he took her into a back office in the store, where he posed as a gynecologist and gave her an exam.

Though the account, contained in court papers, convinced authorities the pharmacist lied to the woman, he may never be prosecuted because of a half-century-old state law that says an assault can’t be considered rape if consent is obtained through fraud or deceit.

The case has added to a debate about whether the law should be changed, and intensified fears that if it stays on the books, it could deter sexual assault victims from coming forward to report the crime.

Hampden County prosecutors dropped a charge last month against Nicholas Creanza, saying by law the actions couldn’t be considered rape. However, they cited a 2007 Supreme Court ruling in which justices urged lawmakers to close the loophole. In that case, the justices determined authorities could not bring a rape charge against a man who was accused of impersonating his brother and having sex with the brother’s girlfriend in a darkened room.

In the pharmacist’s case, the facts “clearly indicate that the victim’s consent was obtained by fraud and deception. However, the Commonwealth is unable to proceed with the prosecution of this case” because of the Supreme Court ruling, Assistant District Attorney Elizabeth Dineen said in court papers.

The court said state law currently defines rape as sexual intercourse compelled by force and against the will of the victim. Fraud cannot replace the force required under the law, the court found.

Wendy Murphy, a Boston attorney and victim’s advocate who teaches a seminar on sexual violence at the New England School of Law, questioned the decision to drop the charges.

“It is not possible to consent to a medical exam by a nonmedical professional,” she said. “If it’s not a medical exam, what’s left? It’s a sexual assault.”

Creanza was arrested in 2005 after two women told police he assaulted them at the Louis & Clark pharmacy in Springfield. One of the women did not go forward with her allegations, a spokesperson for District Attorney William Bennett said Friday.

Bennett did not return calls seeking comment on the decision to drop the charges against Creanza in the other case and whether other charges were possible.