Testifying in a court challenge mounted by McMaster Children's Hospital after it learned the agency would not apprehend the child, he said the hospital should have taken the case to the province's Consent and Capacity Board, which assesses a patient's ability to make decisions about his or her treatment.
He also said the removal of the child would not have been simple or easy.
Neither the patient nor her family can be identified because of a publication ban in the court case surrounding her. The patient's family removed her from the hospital’s treatment plan in favour of traditional healing methods.
The First Nations mother involved says chemotherapy — which her daughter received for 10 days — conflicts with her family's beliefs.
In a letter to CBC News, the mother wrote, “I will not have my daughter treated with poison.… She has to become a healthy mother and a grandmother. I have chosen treatment that will not compromise her well-being and quality of life.”
The mother said the Children's Aid Society investigated, but decided not to intervene. She also said the courts have no jurisdiction over her and her daughter.
In Brantford court, this week, McMaster doctors testified they took the issue to the courts after being frustrated by the lack of communication from the Children's Aid Society after the agency was contacted.
Dr. Vicky Breakey said the doctors did not hear back for days after contacting the society, and thought it had communicated the sense of urgency it felt about the girl's treatment.
Eventually, hospital doctors and Children's Aid did have a meeting, and Koster said he left that meeting thinking the dispute had been resolved. The next day, McMaster initiated the court action.
Koster said that even if Children's Aid had taken the child, it could not force her to take the treatment and would have had to take the step it felt McMaster should have taken initially — bring the case to the Consent and Capacity Board. He said he felt it would have been traumatic to remove the child from her family.
Outside of the hearing, McMaster officials spoke to CBC News in Hamilton last week and defended the decision to take the issue to court.
"Obviously our sole focus is to care for this child that has a life-threatening illness and without treatment will die," said Peter Fitzgerald, president of the McMaster Children’s Hospital.
Fitzgerald said going to court and to demand the Hamilton-region Children's Aid Society to step in and take custody of the child is a rare circumstance.
"We are disappointed that CAS has not carried out their duty to protect the child, and that’s why we’re in court to move this forward," Fitzgerald said.
"This is part of a very long process that we’ve gone through, of course, working with the family, working with the CAS and then finally being in a position where we had to go to court," Fitzgerald said.
"At the end of the day … we know we can save this child’s life. We can’t give up on this child."
Fitzgerald noted the hospital frequently works with Children's Aid, but it’s rare for a case to be a "life and death issue."
Andrea Frolic, the medical ethicist at Hamilton Health Sciences, said that in situations where a substitute decision-maker is believed to be making decisions not in the best interest of a child, health-care providers have a choice whether to refer the case to Children's Aid or Ontario's Consent and Capacity Board.
Because the Children's Aid Socieity's legislated obligation and area of expertise is in the area of child protection, Frolic said, they are often able to mount a timely response.
"It’s a reasonable course of action to refer these situations to that agency," she said.
When asked if it makes a difference that the family is aboriginal, both Frolic and Fitzgerald said that cultural background is considered, but it doesn’t change the course of action for the hospital.
"We spend time understanding [patients'] wishes and values, understanding their world view, understanding what’s important to them — we do that universally with all of our patients and families regardless of their context or their background," Frolic said.
"It’s a fairly clear line of accountability here," Fitzgerald said.
"If we are concerned about the health and welfare of a child, we are legally and morally obligated to contact the CAS."
Fitzgerald said cases like this are difficult for the hospital to deal with because of the limited amount of information they can share, and it can paint the hospital in a "difficult light."
But Fitzgerald said the patient always comes first.
"These decisions are not made lightly," he said.
"We can’t shy away from this responsibility. We need to do the best we can do for this child."
The family left McMaster to seek treatment at a centre that focuses on nutrition and naturopathic therapy in Florida.
The case is similar to another First Nations girl who refused chemotherapy while being treated at McMaster earlier this year. In May, 11-year-old Makayla Sault left treatment at McMaster Children’s Hospital to pursue traditional aboriginal medicine.
Sault's story made national headlines and after an investigation, Children's Aid decided not to intervene and her case never went to court.