A Belfast law firm is to take a case on behalf of a family in Co Armagh over the decision not to close schools in Northern Ireland.
On Sunday, Education Minister Peter Weir insisted schools would only shut in the region when the time is right.
He tweeted: "The time will come when it is right from a public health point of view that schools will need to close. Schools and parents/guardians should begin to plan arrangements for that long period of closure including childcare for their children."
Schools in the Republic closed for a fortnight on Friday.
In a statement, Belfast law firm Phoenix Law said: "We are instructed by the mother of a child who attends a primary school in County Armagh.
"Our client's daughter suffers underlying health problems, including severe asthma and therefore is at a greater risk of harm should she contract the Coronavirus.
"It is our client's case that the current position is unlawful and contrary to the necessary protections afforded to all citizens under the human rights act.
For these reasons, we have been instructed to put the various public bodies on notice of our intention to apply for judicial review."
Darragh Mackin, a solicitor at Phoenix Law who acts for the mother, said: "It is clear that the respective public bodies have each failed in their respective obligations to our client, and indeed all children, by continuing to require their attendance at school in circumstances in which they would be at an increased risk of contracting the condition.
"There is no time for any further delay. The necessary policies and decisions all need to be taken in a manner that recognises the real and immediate risk.
"The wider international community has spoken. Their advice cannot and should not be ignored."
On Sunday, 11 new cases of coronavirus were confirmed in Northern Ireland, the Department of Health announced.
This brings the total number of confirmed cases in Northern Ireland to 45 and is the biggest one-day increase in the region to date.
It comes as special schools in Belfast have announced that they will close from Monday.
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