Attorney General Eric Holder said the new definition will lead to a more comprehensive reporting of rape in the FBI's annual compilation of crime statistics.
"These long overdue updates to the definition of rape will help ensure justice for those whose lives have been devastated by sexual violence and reflect the Department of Justice's commitment to standing with rape victims," Holder said. "This new, more inclusive definition will provide us with a more accurate understanding of the scope and volume of these crimes."
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An FBI advisory panel recently recommended the revision to the antiquated definition, established in 1927.
The law then defined rape as "the carnal knowledge of a female, forcibly and against her will." That meant that it was only an act of rape if a man forcibly penetrated a woman through her vagina. It excluded oral and anal penetration; rape of males; penetration of the vagina and anus with an object or body part other than the penis; rape of females by females; and non-forcible rape.
Under the old definition, the case of former Penn State assistant coach Jerry Sandusky -- charged with 40 counts in what authorities allege was the sexual abuse of young boys -- would not be considered as rape.
"Needless to say we are very pleased that the FBI has agreed to revise its definition used in data collection so it more accurately reflects what the public understands to be rape and what our current criminal statutes say," said Carol Tracy, executive director of the Women's Law Project, which has been pushing for the definition change.