Is there some established definition of “sex ring”? Ring: a group of people drawn together due to a shared interest or goal, especially one involving illegal o

Is there some established definition of “sex ring”? Ring: a group of people drawn together due to a shared interest or goal, especially one involving illegal or unscrupulous activity. "the police had been investigating the drug ring" could we maybe be a bit more specific? Is the claim that this was a “prostitution” ring, which would be illegal, though possibly not immoral unless there was coercion? Or was this just a group of people having “sex”, which I believe is still legal in the United States?