The Ontario government has ordered hundreds of adoption cases to stop moving forward while a judge reviews whether the children should have been put up for adoption in the first place, CBC News has learned.

The move has put as many as 300 families in legal limbo, not knowing when — or if — their adoptions will be finalized. 

It comes in the wake of the scandal over the Motherisk drug-testing program run by Toronto's Hospital for Sick Children. The laboratory analysed the hair of babies to test for drug and alcohol use by their moms, and the results were used as evidence in the cases of thousands of children taken into care by children's aid societies.

"Any active adoption where a Motherisk test has been a factor in the case will be put on hold until it can be reviewed," said Aly Vitunski, press secretary to Children and Youth Services Minister Tracey MacCharles.

Some 200 to 300 families trying to adopt are now being told of the pause, said Mary Ballantyne, chief executive of the Ontario Association of Children's Aid Societies.

"Certainly upset, frustration, concern would be what these families would be feeling at this point in time," Ballantyne said in a phone interview. 

Some of the families have reached out to Adopt4Life, a provincial support group for adoptive parents. "Families are pretty stressed and frightened about the fact that their adoption is not moving forwards," Julie Despaties, the group's founder, said in a phone interview. 

"They don't know when things will get resolved," Despaties said. "There's a sense of urgency and panic not knowing, because there's no answer, no one can provide them a date that the process will restart."

Sick Kids hospital sign

The Hospital for Sick Children shut down the Motherisk drug-testing lab in April 2015. (CBC)

The government is not putting a timeline on reviewing the adoption cases that are already in process. 

"We know that it's important that these cases be expedited which is why they will be triaged and given priority for review," Vitunski said in an email. 

Some 9,000 people tested positive for drug use according to the Motherisk lab at Sick Kids from 2005 to 2015. The test results were primarily used in child protection cases in Family Court by children's aid societies to argue that kids should be taken from their parents and into care. 

The flawed tests would not have been a key factor in every case when a child was apprehended, but may have unjustly influenced the decisions in some, said retired appeal court justice Susan Lang in her report on Motherisk in December, 

Sick Kids shut down the lab last spring.