Karen B., a Los Angeles writer in her 40s, found a sperm donor on Craigslist when decided to have a baby that she would later raise with her lesbian partner.
"I tried every male friend, gay, straight, married and single, but it was really difficult to find somebody," said Karen. "I was running out of options and my biological clock was ticking."
After connecting on the Internet, she and the donor, Daniel C., signed a layman's agreement that the child would live with Karen and she would make all parenting decisions. He would have some visitation rights.
"I always wanted the baby to know the father," said Karen, who had originally intended to use a family friend's sperm until she discovered he was HIV positive.
But as the pregnancy progressed, Daniel interjected himself into the couple's life, telling the doctor he was Karen's husband, even though he was gay.
After the birth, Daniel insisted Karen get a passport for the boy, so he could visit his native Brazil. When she refused, Daniel sued her for joint legal and physical custody.
There are no exact numbers, but using a known, rather than an anonymous sperm donor is becoming more common, especially in the gay community. Parenting agreements between mother and sperm donor, like the ones Karen and Daniel signed, can readily be found online.
But these casual arrangements, which are co-brokered at gay mixers and online, can throw new families into turmoil when relationships go sour or a sperm donor changes his mind.
The case also raises questions not only about whether sperm donors have parental rights, but what is best for the child now that reproductive technologies are creating new kinds of families.
The courts eventually ruled in favor of Karen, allowing the sperm donor to visit twice a month, but Daniel's involvement in her son's life has continued to be problematic.
In July, the Superior Court in Santa Monica, Calif. rejected Daniel's claim under the California's Sperm Donor Statute, even though his name was on the birth certificate.
"The decision in this case upholds the law, which was put into effect to protect both sperm donors and recipients -- whether they are married, unmarried, gay or straight," said Karen's lawyer, Ilene Trabolsi. "The law affords a statutory vehicle so that men are free to donate their sperm without fear of liability for child support and women can obtain semen for artificial insemination without the fear that the donor may claim paternity."
Karen ended up spending $60,000 in legal fees to fight the case, and she often wonders if Daniel will take her son, who is now 3, to Brazil during twice monthly visitations.
"A lot of my friends are concerned he's a flight risk," she Karen. "It makes me nervous. I let him see my son for four hours, but if he's 10 minutes late I panic."
Karen came forward to tell her story to help others.
"Women should use caution," she said. "I know a lot of gay and straight friends who are contemplating using a friend and I think they are unaware of the potential dangers of doing this."
Daniel's identity could not be revealed because the case was a closed paternity suit. But according to Trabolsi, his lawyers argued that because Karen had signed a voluntary declaration of paternity and Daniel's name was on the birth certificate, he should be considered the legal father.
Karen said she was handed the so-called "POPS" agreement "drugged" while on pain medicine after the Caesarian birth and had no idea what she was signing.
These hospital forms are typically used by the state to protect mothers from "deadbeat dads" and are invoked in child support cases. But in Karen's case, the agreement was used against her, according to Trabolsi.
From the beginning, Karen said she didn't want her child's father to be a "mystery."
"I have a female friend who is the product of sperm donation and they didn't keep records," she said. "Every single day of her life, she was bothered by the identity of her father."
When she met Daniel, who worked in retail, he "seemed sincere," according to Karen. "He brought me a big bag of groceries and all his diplomas and childhood pictures. He wanted me to know he was a decent guy."
In their agreement, she absolved Daniel of any financial obligation. He agreed that her partner could adopt the child.
"I saw red flags and a number of white lies," she said. "But it didn't dawn on me until I was pregnant and past the point of no return."
And when her son was only eight months old, Daniel pressed upon her to let him take the child to Brazil.
"It was ridiculous. I was still nursing," she said.
Karen said she tried to placate him, but days later Daniel served her with legal papers.
In one of the more famous cases of acquaintance donors, rock star David Crosby, 69, donated his sperm to friend and singer Melissa Etheridge and her former lesbian lover Julie Cypher, who had two children born in 1998 and 2000.
"It's very kind of them both to let me spend time with the kids, because our official deal was that I signed papers relinquishing parental rights of any sort after I made my gift," he has told People magazine. "They're great kids, they're very special people in my life."
The couple has subsequently divorced and Crosby has said he would not have donated sperm, had he known his friends would split up.
Linda Elrod, director of the Children and Family Law Center at Washburn University Law School, testified in a similar case in Kansas in 2007 when a sperm donor sued a single mother who was a friend, after she gave birth to twins.
The donor wanted to share parenting, but the court ruled that sperm provided for artificial insemination is not the legal father without the mother's agreement in writing.
But Elrod, who argued on behalf of the children, said that a "known genetic father" who wants to accept parental responsibility should have those rights.
Until there is more regulation in the reproductive industry, "We are going to see more of this" and the law "isn't quite ready" to accept more than two parents, she said.
"What is the power and control stuff?" said Elrod. "Why not do what's best for the kids, rather than what's best for the parents?"
"We do violence to children to drive out or not allow them to have relationships that can help them financially or emotionally," she said. "Why not allow for more than two parents? Having a psychological parent and a biological parent expands their horizons."
She said that at some point the law will have to allow more than two people to be involved in a child's life, when it benefits and is not harmful to the child.
In the case of Daniel and Karen, he has continued to be a part of Karen and her son's life, but she has regrets about not choosing an anonymous donor.
The visitations have been psychologically confusing for her son, according to Karen. Daniel showers him with material gifts and tells the boy he shouldn't call Karen's partner, "mommy."
The lawsuit was harrowing on Karen, too.
"It was almost two years in and out of court, dealing with horrible emotional stress," she said. "The legal fees could have been my son's education."
Her lawyer said women should rely on the California statute to protect their parenting rights and never enter into private agreements.
"[Daniel] really did become a stalker," said Trabolsi. "He wanted so much to be a part of Karen's life…Whatever his motivation was -- it became such a nightmare for Karen."
"She had such lofty goals – she thought this would be the ultimate gift to her child," said the lawyer. "But it was an idyllic picture that went wrong."
Karen agreed: "It was a beautiful situation that backfired."