Objections have been lodged against moves to celebrate Hercules Mulligan in the Causeway Coast and Glens area.
It comes after records showed he owned a slave after helping to set up an anti-slavery society.
Mulligan s family emigrated to America in 1746, when he was six. He went on to spy on the British during the American War of Independence and in 1785 was a founder member of the New York Manumission Society, which campaigned to abolish slavery.
According to official US records, however, he still owned a slave five years after establishing the organisation, with one even living with his family.
Alliance councillor Yvonne Boyle, who proposed that Mulligan be recognised through local heritage trails, said she knew he had owned a slave before she put forward the motion.