A lawsuit against a well-known Ottawa fertility doctor involving allegations of a sperm mix-up could turn into a criminal matter if the parents' worst fears are realized.

Trudy Moore and her husband Matthew Guest, and another patient, single mom Jacqueline Slinn, are suing Dr. Norman Barwin and his Broadview Fertility Clinic for $3 million, alleging he failed to ensure the right sperm was used in their treatments and then failed to tell them.

Not only do the parents allege Barwin used the wrong sperm; they are now worried he may have used his own sperm.

Both parties have asked the court to order Dr. Barwin to submit to a blood test, to rule out "the possibility that he is the donor whose sperm was used to inseminate."

For now, the case is a civil matter. But Nancy Lam, a surrogacy lawyer who practises fertility law in Toronto, tells CTV's Canada AM that the case could potentially result in criminal charges, "depending on how [police] want to proceed and if the government wants to get involved."

"For now, it's just a matter between the parties," she said, noting that there is no legal precedent for such a case in Canada, as far as she is aware.

Moore and Guest allege in court documents that a blood test confirms Guest is not the father of their child, born in 2007 to a surrogate. They ordered the test after noticing their child did not resemble his father.

Slinn, meanwhile, says a blood test also proves she was not inseminated with her chosen donor's sperm. She had her baby tested after contacting other women who had used the same donor. She found her child's DNA did not match the other children's.

Pam MacEachern, the lawyer representing both families, told CTV Ottawa that based on evidence she has heard, "we believe that it probably happened in other situations."

MacEachern has filed two lawsuits launched in Ontario Superior Court seeking damages for "heightened anxiety, depression and frustration," among other things, suffered by the families.

Lam says the lawsuit will likely involve accusation of breach of contract, and of negligence, if it's shown that the doctor and the fertility clinic failed to ensure properly that the right sperm was used.

Dr. Barwin has denied any wrongdoing and has asked asking the Ontario Superior Court to dismiss the cases.

Barwin is one of the world's leading fertility doctors. A native of South Africa, he has practised for decades and is a member of the Order of Canada.

Dr. Art Leader of the Ottawa Fertility Centre said he knows Barwin, and can't imagine he intentionally mixed up donor sperm samples.

"Dr. Barwin has always been a caring physician who has cared for his patients and has been dedicated to the care of the infertile," Leader said.

Barwin continues to work at his Ottawa clinic.

With a report from CTV Ottawa's Catherine Lathem