KANSAS CITY, Mo. (AP) — Advocates for people who engage in rough but consensual sex say they fear an abuse case unfolding in Missouri ultimately could criminalize their lifestyle.

Ed Bagley faces a federal trial early next year on 11 counts of abuse against a woman authorities say he groomed to be his sex slave. Now prosecutors plan to present consensual, though violent, acts between Bagley and his own wife as evidence that Bagley has a history of sexually assaulting women.

The case will include evidence of “sadistic sexual assaults” committed by Bagley against his wife, Marilyn, prosecutors say.

“Marilyn Bagley’s ‘consent’ to the sexual assaults by Defendant Edward Bagley does not change whether the acts legally constitute assault or not. Pursuant to the Missouri state assault statute … consent is not a defense to assault resulting in serious physical injury,” prosecutors wrote in court documents filed last month.

Some worry the government’s assertion could open up people who practice bondage, dominance, sadism and masochism — or BDSM — to criminal charges for consensual acts they’re already performing, said Susan Wright, founder of the Baltimore-based National Coalition for Sexual Freedom.

“We are following this case specifically because we were hoping this issue would not come up,” she said.

Ed Bagley, 45, of Lebanon, Mo., is accused of grooming a young woman to be his sex slave starting in 2002, then keeping her captive for years while making money from her images on fetish Internet sites and forcing her to work as a dancer at strip clubs. Marilyn Bagley, 47, is charged with five counts, including sex trafficking and forced labor trafficking.

Both have pleaded not guilty and are scheduled for trial in February.

Prosecutors claim Bagley, known as “Master Ed,” tortured the young woman and made her available to other men who came to his trailer, either to torture or have sex with her. Four men, who said they visited Bagley’s trailer to watch or take part, have pleaded guilty to conspiracy charges.

The case came to light in early 2009 after the woman, then 23, was hospitalized after what prosecutors said was a torture session. Then-U.S. Attorney Beth Phillips called the case one of “the most horrific ever prosecuted in this district.”

Advocates for the BDSM community say even the most brutal acts detailed in Bagley’s federal indictment are not criminal acts, as long as there was consent. But if the woman was too young or not intelligent enough to consent, as prosecutors allege, or if she initially gave consent and then changed her mind, most who spoke with the AP said that would be criminal sexual abuse.

It’s the inclusion of Bagley’s acts with his wife in the case that concerns BDSM advocates and Bagley’s attorney, Susan Dill.

“Like many people from all walks of life, my client and his wife engaged in what some might term alternative, but nonetheless, consensual sexual activity that they both enjoyed,” Dill said in an email to The Associated Press. “The assertion that their consensual, marital sex life is evidence of prior criminal activity is nonsensical.”

As in several other states, Missouri assault laws limit instances in which consent can be used as a defense against criminal charges when serious injuries occur. Exceptions generally are made for athletic activities and the victim’s occupation or professions in which the conduct and harm are reasonably foreseeable hazards.

Wright’s group contends “serious physical injury” is not well-defined under law.

“The assessment of the seriousness of harm is often affected by judges’ ‘moral judgments about the iniquity of the conduct,’” the organization says on its website in a section focusing on the consent issue. “Courts tend to inflate the risk and harmfulness of an activity they want to denounce. For example, any injury caused during a sadomasochistic encounter has been consistently classified as serious.”

Diana Adams, a New York attorney and sexual freedom activist who represents clients in alternative lifestyles, said the landmark 2003 U.S. Supreme Court ruling “Lawrence v. Texas” that struck down a Texas anti-sodomy law “declared we had a right to consensual sex between adults in the privacy of our own homes,” but that the law is not clearly defined.

“In this kind of case, sometimes it’s selectively applied,” Adams said.

She said federal courts in Texas and Alabama interpreted the Lawrence decision in different ways in 2004. The Texas court used the case to strike down a ban on sales of sex toys, citing Lawrence’s privacy conclusion. The Alabama court, however, upheld a similar ban by saying commercial sale of the toys was an issue of obscenity, not privacy.

Wright notes that regardless of the legal precedent, prosecutors’ attempts to present acts between Bagley and his wife as evidence in the Missouri case also comes at a time when kinky sex practices appear to be gaining broader public acceptance amid the popularity of the E.L. James “50 Shades of Grey” bondage books.

“Because of ‘50 Shades of Grey,’ a lot of people are trying BDSM for the first time this year,” she said. “We want to be sure they understand they have to do these activities consensually, and to make sure they have the skill to do them safely.”

• Associated Press