(WBIR) - Our NBC News partners at WBIR are reporting that cheek to cheek, they danced so slowly their feet barely lifted from the floor, the cover band playing "When You Say Nothing at All."

The old country song is an apt description of Rosemary and Coy Maness's love story as they celebrated their one-year wedding anniversary. It distills the essence of true love into its most basic expressions: a smile, a touch. "Without saying a word, you can light up the dark," the lyrics say.

Both Rosemary Maness, 63, and Coy Maness, 54, have intellectual disabilities, defined as an IQ of 70 or lower. Around them at the spring dance were others with similar disabilities — people on dates, people hoping to find a date, people socializing with friends. Asked about her marriage, Rosemary Maness patted her chest and said, "He's just ... my heart."

Yet the rights of people with intellectual disabilities to date, to choose an intimate partner and to marry remain controversial.

Decades into a movement to recognize that people with intellectual disabilities should live as independently as possible and make their own decisions, sexuality and relationships remain among the last frontiers, advocates say.

"This is like the elephant in the room that everyone walks around," said Beverly Frantz, an expert on intellectual disabilities and sexuality at the Institute on Disabilities at Philadelphia-based Temple University.

In Tennessee, the desires of individuals for relationships often run headlong into thorny questions about whether an individual has the capacity to make an informed decision about sex, dating or romance. They also run into state laws that criminalize a sexual relationship when either or both individuals are "mentally defective." The law is intended to protect vulnerable people from exploitation, but it has also had a chilling effect on private care agencies and conservators, who fear they could be held liable if a person in their care engages in a sexual relationship.

No policy at DIDD

There's no policy set by the state Department of Intellectual and Developmental Disabilities, which provides care to 8,000 individuals. Instead, the wishes of parents or conservators and the philosophy of private care providers determine who can and cannot pursue a relationship.

Many people with intellectual disabilities yearn for intimacy — for sex, love and marriage, said Katie Powers, an administrator with Developmental Services of Dickson County. Her agency provides caretakers for Rosemary and Coy Maness, who met at agency dances and outings, decided to marry and approached Powers with their decision.

"Their IQ doesn't determine their feelings or needs," she said. "So many of our folks are lonely. They don't get a lot of touch or a lot of affection. And, to be honest, a lot of them want sex, just like anybody else."

When Rosemary Maness first said she wanted to marry, Powers advised her to wait a few months to think it over.

"But she just said, 'no,' and marched out mad as a snake," Powers said. "She knew her mind. And then Coy came in and said, 'She has cancer. Why do we need to wait?' " The couple married two months later, after some frank counseling on sex and intimacy, Powers said.

But there are also individuals with severe disabilities who do not have the capacity to make such decisions, and for whom intimate relationships are not appropriate.

A 68-year-old Columbia, Tenn., pastor faces rape charges stemming from allegations he had a sexual relationship with an 18-year-old woman with intellectual disabilities. The allegations came to light after the young woman told her mother about the relationship.

While the relationship would raise moral and ethical questions even if the woman did not have a disability, it resulted in criminal charges only because she did. David Zeigler is being prosecuted under the portion of state law that defines rape, in part, as when a perpetrator "knows or has reason to believe that the victim is mentally defective, mentally incapacitated or physically helpless."

'A sticky issue'

The same law has had a chilling effect on private care agencies and on conservators, concerned about legal liabilities.

Comcare is a nonprofit agency appointed to be legal conservator to about 1,000 people across the state. Director Dr. John Johnson said that while the agency has no authority to restrict relationships, "we keep running up against the law."

"It's a sticky issue, because a group of friends cannot make that decision, a parent can't make that decision, a provider can't make that decision," Johnson said. "We have to go back to that statute. If the person engages in sexual relations and after the fact someone determines that they did not have capacity to consent, it's the person who engaged in sexual relations with that person who is in trouble, as well as anyone who facilitated it."

Comare's position is that a psychiatric professional would need to evaluate an individual's capacity to make an informed decision before allowing him or her to embark on a relationship. Johnson acknowledges that could be a long, costly process.

Parents have their own concerns.

Julie Ferrell's 38-year-old daughter, Heather, has had several boyfriends. Heather Ferrell is intellectually disabled and struggles with mental illness. She is largely nonverbal.

"To Heather, having a boyfriend just means holding hands," said Julie Ferrell. One of her worst fears is that her daughter, trusting by nature, will be taken advantage of. Once, she said, a man her daughter dated put his hand down her shirt, a frightening experience.

"They see the world as it should be, but I see the world as it is, and there are a lot of undesirables out there," Julie Ferrell said.

Limited guidance

The state offers parents, guardians and agencies limited guidance. DIDD officials recently updated their manual for private agencies to say that "individuals have a right to have intimate relationships with other people of their choosing, unless such rights have been specifically restricted by a court order."

Spokeswoman Cara Kumari noted that this is not an official policy, just a statement about the rights of people in their care.

"Relationships are personal matters, and issues involving relationships are handled on an individual basis," Kumari said.

Powers said a lack of guidance means that individuals' freedoms will continue to depend on their immediate caretakers and family members, rather than on an objective assessment of what each person could experience in life.

"You talk to anyone here," she said. "The women all want to be married. Most never will be, but we can't take away that chance simply because we don't want to deal with uncomfortable issues."

For Rosemary Maness, there's nothing uncomfortable about her relationship with her husband.

""I couldn't love nobody else but him," she said. "Even if I would have to live alone, I would stay alone. It's only him."