The Immigrant Council of Ireland has said 2,000 people could be affected by the State's plan to deport the non-EU spouses of EU citizens from outside Ireland if the spouses are living here illegally.
The Department of Justice stated it had the right to deport non-EU spouses following a High Court ruling two months ago.
The ruling affects people from outside the European Economic Area - made up of the 27 EU member states and four other nations - who have married an EU citizen who is not Irish.
The ICI says that 'huge disruption' has been caused to people who came to Ireland in good faith and who are being refused permission to live here.
Speaking on RTÉ Radio's Morning Ireland, solicitor Derek Stewart said if the purpose of the move was to crackdown on convenience marriages, it would be to the detriment of the majority who were genuine couples.
The Department of Justice issued notices of intention to deport following a court ruling.
In June the High Court ruled that the Department of Justice had the right to insist that wives or husbands of non-Irish EU citizens, who were not from the EU themselves, must live legally in another member state before moving to Ireland.
That judgment is being appealed in the Supreme Court but in the meantime the Department has issued deportation notices informing the non-EU spouses living in Ireland of the implementation.
The section 3 letters give those under threat of deportation three options: to leave voluntarily; to agree to be deported; or to make representations to stay in Ireland temporarily within the next 15 days.