A bitterly disputed, government-sponsored study has concluded that rape and sexual assault behind bars may be rampant in movies and books but are rare in real life.

When inmates have sex, it is usually by choice, and often engaged in as a way to win protection or privileges, said Mark Fleisher, a cultural anthropologist who specializes in prisons and crime at Case Western Reserve University in Cleveland, Ohio. He said inmates who cry rape are usually lying and looking for a transfer, money or publicity. The two-year study, commissioned by the U.S. Justice Department for $939,233 US, has come under withering attack from other experts. The department has not endorsed the study, saying Fleisher has yet to turn over his data for closer examination.

"To take the position that it's not a problem and prisons are safe places is asinine," said Reggie Walton, a federal judge and chairman of the National Prison Rape Elimination Commission, set up under a 2003 federal law. He said Fleisher's conclusions are "totally inconsistent" with what he has learned during 30 years in the criminal justice system.

Cindy Struckman-Johnson, professor of psychology at the University of South Dakota and one of nine commission members, said Fleisher's 155-page study is not in scientific form. She said there is no literature review, no raw data, and no in-depth explanation of his subjects or research methods. Fleisher said he spent more than 700 hours interviewing 564 randomly chosen inmates at dozens of institutions across the country. He said he never met anyone who claimed to be a victim of sexual violence.

Justice Department spokeswoman Catherine Sanders said Fleisher's report is being peer-reviewed and is not considered finished. However, Fleisher co-wrote an article about it in The Criminologist, the American Society of Criminology's newsletter. Speaking on condition of anonymity, a Justice Department official familiar with the findings said that the department is trying to determine whether the conclusions are supported by the data, but that Fleisher has not shown his evidence to anyone.