When Mary Tolley was nine months old, a fever damaged her brain, leaving her severely mentally retarded. Now, at 17, she cannot wash clothes, cook meals or carry on a conversation.

But Mary is not devoid of ability. Last week, she sat in her parents' home in Montgomery County's Cloverly community, nimbly fitting together pieces of a complex jigsaw puzzle until a big-eared picture of Mickey Mouse took form.

Across the room, her mother sorted through a different, more vexing puzzle. Joyce Tolley wants to have Mary sterilized, but state courts forbid nontherapeutic sterilizations.

Tolley and Judith Hagar, the mother of a retarded daughter, were active in organizing about 50 Montgomery County parents of mentally retarded children, who are asking the General Assembly to empower judges to sanction sterilizations. The group of parents held its second meeting last week at the county's Longview school for retarded students.

"This is the most controversial issue around, next to capital punishment and abortion," said Del. Judith C. Toth, a Montgomery County Democrat, from whom the parents have sought help. "It raises serious questions about the moral role of government in individual lives."

A sterilization controversy erupted in Virginia earlier this year when state health records were discovered that revealed the sterilization of more than 7,500 persons confined in six mental institutions during a 48-year-long program which state authorities at the time said was aimed at eliminating social misfits and promoting genetic purity. The sterilizations were sometimes performed without the consent or knowledge of the persons on whom the operations were performed.

Toth said she is "working on drafting" a bill for the Maryland legislature but finds "it is very difficult to come up with something that protects the rights of every individual."

The parents, she said, "are talking about sterilizing their children, who can marry, enter contracts, . . . work, pay taxes and live in group homes. It's rather difficult to go in there and say, 'We don't want the girl to get pregnant.'"

Montgomery Democrat Joseph E. Owens, chairman of the House judicial committee that Toth said would consider her bill after it is introduced, warns that Maryland legislators may encounter constitutional questions about sterilizing persons without their consent.

In response, Joyce Tolley says, "I think these rights people are going overboard. The United State Supreme Court made wholesale abortion simple, allowing a living being to be killed, and we can't even prevent someone from getting pregnant. It doesn't make any sense to me."

Tolley's daughter, Mary, has never dated and Tolley said Mary shows no sign of understanding sex.

"What I'm worried about is rape. I'm 31 years older than she is and I assume I'm going to die before she does. I don't know what is going to happen to her then. I hope and pray she doesn't end up in an institution. My god, if she got pregnant it would ruin her life. She can't even take care of herself, let alone a baby."

More than a year ago, Tolley read about a montgomery County Circuit Court ruling -- in Flanary v. Flanary -- that prevented a doctor at Montgomery County General Hospital from performing a hysterectomy on 11-year-old Sonya Star Flanary, who was left blind and permanently disabled when she suffered brain damage in a car accident.

On Dec. 11, 1979, Circuit Court Judge John Mitchell ruled that he lacked authority to approve the sterilization surgery on Flanary. The case was appealed to the Court of Appeals, the state's highest court, which upheld Mitchell's ruling.

Tolley was shocked by the court's action: "I had always planned to have Mary sterilized, but I realized that the court didn't have the power to authorize it . . . The General Assembly needs to pass legislation giving us the right to make decisions for our children."

Raymond P. Ragosta, a psychologist at the Forest Haven Residential Facility for the Mentally Retarded in Washington, called the sterilization movement a troubling, emotional issue that threatens to increase, not reduce, the problems faced by mentally retarded citizens.

"No one has the right to make these kinds of decisions for them, unless they are declared incompetent by the courts. The impact of sterilization is that it is just one more blow to their self-esteem. It makes them that much different and that much more abnormal. You have to remember, retardation is not a disease, it's a condition, a handicap like blindness," he said.

Ragosta, who has spent 15 years in the mental health field, worked at Rosewood Center in Owings Mill and the Great Oaks Center in Silver Spring, two residential care facilities in Maryland. "Mentally retarded people have the same rights as everyone else," he said, "even though they are being violated every day.

"The problem with a law on sterilization is where do you draw the line, at an IQ of 60, 65, 70 or where?"

"The great myth of mental retardation is that they are going to raise more mentally retarded children. Very few of the retarded have genetic defects, and we know that parental IQs don't correlate with children's IQs. We have a lot of very smart people who raised mentally retarded children. There is nothing in the Constitution that says in order to procreate, your cognitive abilities have to be on par with the rest of society."

Ragosta advocates holding a long series of public hearings before Maryland's General Assembly considers a sterilization law."We need to hear from specialists in the field, not a bunch of hysterical reactions from emotionally involved parents.This is a tough question. After all, we are talking about 2 percent of the population and we know as (little) about them as we do about the Einsteins of the world."

Among the opponents of sterilization is the American Civil Liberties Union.

Leslie Harris, the executive director of the National Capital ACLU, said: "The first point is that everybody has a constitutional right to privacy, including the retarded.Our concern has to do with the people who are sterilized, and then rehabilitated."

Joyce Tolley and Judith Hagar said they feel trapped by shifting social forces. On one hand, mentally retarded citizens now participate more actively in society, ending decades of being home bound or institutionalized. But the two women say the newly won freedoms hold the danger that the retarded will irresponsibly engage in sex, or be raped.

Tolley said she has not discussed sterilization with her daughter, explaining, "I don't see the point. I don't think she'd have the foggiest idea of what i'm talking about."

Mary is enrolled in the Longview School, but she is now at home. Her mother said that Mary does not like school and periodically refuses to attend classes.

Mary is 5 feet, 4 inches tall and weighs 235 pounds. "That makes it almost impossible for me to move her around if she doesn't want to do something," her mother said.

Hagar said she has talked to Debbie, her 13-year-old, mentally retarded daughter, who Hagar claims understands what it means to have a baby. "I asked her if she thought she could baby-sit, or have a baby, and she said, 'No.'"

"Debbie has been to camp the last three years and she is now aware of her sexual development and drive. She is fully able to conceive. If she became pregnant, it would destroy her physically and psychologically," Hagar said.

A third family seeking the legislative go-ahead for sterilization, William and Yates Barreda of Silver Spring, wants the court to approve a tubal ligation on Kate, their 15-year-old daughter who attends the Stephen Knolls School in Montgomery County.

Kate is a victim of Down's syndrome (formerly known as mongoloidism), a condition induced by chromosomal defects.

"My concern," said her mother, "is that she has a chance, not a great one, but a slim one, of living in the community, in a group home, holding a job and living independently. If she got pregnant, it would ruin that. We looked into having her sterilized and found out that no one would do it.

"She is aware of her sexuality. She is interested in having boyfriends. She masturbates and she is aware that people get married and have children. But she doens't understand conception, not at this point," said Barreda.

The three families -- the Barredas, Hagars and Tolleys -- said they have rejected less drastic forms of birth control, such as intrauterine devices and pills, because they fear medical complications might result or that the children cannot be trusted to take pills regularly.

A sterilization bill may be introduced as early as next week, but it is unlikely that the assembly will move on it during the 1981 session, Delegate Toth said.

If the lawmakers don't take action, the courts may. A new petition in the Flanary case has been filed in Montgomery County Circuit Court, seeking court clearance, once again, for doctors to surgically sterilize Sonya Flanary. A hearing has been scheduled for March 6.