Do the norms of a sadomasochistic erotic subculture even matter in a case of alleged sex trafficking?

That question probably will be answered soon after a hearing next week at which lawyers will argue the relevance of such evidence at the trial early next year of Edward and Marilyn Bagley. The Lebanon, Mo., couple are accused of sex trafficking a young woman for several years.

For a year, prosecutors and defense lawyers have jousted over the qualifications of expert witnesses who would testify as to whether Edward Bagley’s conduct with the young woman conformed to the practices of the bondage, discipline and sadomasochism, or BDSM, lifestyle.

Prosecutors have alleged that in 2002, Bagley persuaded a 16-year-old girl to live with him and later coerced her into becoming his sex slave. Bagley purportedly tortured her, with the help of other defendants, until she was hospitalized in February 2009.

The techniques allegedly ranged from waterboarding and electric shock to piercing and mutilation.

In court records, a government expert already has opined that the young woman was “tortured,” while defense lawyers have argued that the conduct was “legal” and “consensual.”

Judges often permit testimony from witnesses designated as experts because of their education, training or unique life experiences. They explain areas with which jurors may be unfamiliar, such as complex financial matters or scientific forensic evidence.

And though unusual, experts sometimes are called to address exotic sexual subcultures unexplored by the typical juror.

The government’s expert is the well-traveled Park Dietz, a California forensic psychiatrist who testified in the cases against Jeffrey Dahmer, John W. Hinckley Jr. and Andrea Yates. Dietz also testified for federal prosecutors here at the 2007 trial of Lisa Montgomery for the killing of Bobbie Jo Stinnett and the kidnapping of her unborn baby.

Prosecutors asked Dietz to be prepared to testify about what is appropriate and accepted “within the rules and regulations of the BDSM lifestyle” and what clearly exceeds them. Dietz’s bill to the government could run up to $84,900, prosecutors estimated.

He also is expected to testify about other aspects of the case.

To counter Dietz, Bagley’s lawyer asked the court to pay $32,900 for her own expert — Jay Wiseman, a California lawyer, lecturer, author and, since 1975, an active member of the San Francisco Bay area sadomasochism community, according to his resume on file with the court.

“Wiseman is uniquely qualified to provide insight to the court and jury as to whether the conduct engaged in by the defendants and alleged victim are as extreme and sadistic as the government would have the world believe,” wrote Susan Dill, Edward Bagley’s defense lawyer.

But U.S. District Judge Dean Whipple wrote recently that he is still not convinced that expert testimony on the BDSM subculture would be admissible for either side at trial.

“Instead, it appears that the main issue is whether the alleged victim consented to the conduct complained of,” Whipple wrote in an order setting next week’s hearing.