Baroness O'Loan has made an urgent appeal to Northern Ireland secretary Julian Smith to recall the Assembly in a last ditch bid to stop radical new abortion laws coming into effect in the province.
Her call has been backed by over 24,000 people in Northern Ireland who have signed her petition on Change.org.
An amendment passed by MPs in Westminster to allow abortions up to 28 weeks is days away from becoming law in the country, despite widespread opposition.
In her letter to Smith, Baroness O'Loan said that the ongoing suspension of the Northern Ireland Assembly was "most unsatisfactory" and that there were "significant legal uncertainties" surrounding the new abortion laws that needed to be resolved by the province's own representatives.
She urged Smith to "respond positively" to the call "given the urgency of the situation", and warned of a "legislative and administrative lacuna" when the changes come into force on October 22.
"We need our own legislature to deal with matters relating to Brexit, to all the numerous and urgent problems which exist in Northern Ireland, and most of all to deal with the difficulty of the situation with regard to abortion if the Assembly and Executive are not reformed," she said.
"This situation is unprecedented. Despite the recent publication of guidelines there is an enormous lack of clarity about the situation which will prevail between 22 October and the introduction of new regulations.
"There are significant legal uncertainties pursuant to the publication of those guidelines, and in the absence of any legal certainty which might derive from properly articulated legislation, they give rise to great concern for the safety of mothers and their unborn babies, and about the absence of any clear statement of the legal rights and obligations of those who might be affected by the guidelines."
She continued: "The legislative and administrative lacuna which will occur on Tuesday next will mean that there will then be no specific laws regulating the conduct of individuals who, or institutions which provide abortion services in Northern Ireland between 22 October and the passing of further new law.
"Effectively we will be back into the situation which prevailed before 1803."
A new poll of 1,424 people in Northern Ireland has revealed the strength of concern around the changes.
Over half of those surveyed (52%) by LucidTalk on behalf of Both Lives Matter said they did not support the changes voted through by Westminster, compared to 39% who said they backed the measures.
When it comes to negotiations to restore the Assembly, nearly half (49%) said they wanted the safeguarding of explicit legal protections for every unborn child up to 28 weeks.
