The case which cemented Curran's popularity was that of Father Neale and St Leger St Leger, 1st Viscount Doneraile at the County Cork Assizes in 1780. Father Neale, an elderly Catholic priest in County Cork, criticised an adulterous parishioner. The adulterer's sister was mistress to Lord Doneraile, a cruel Protestant landlord. Doneraile demanded that Neale recant his criticism of his mistress' brother. When the priest stood by his principles, Doneraile horse-whipped him, secure in the confidence that a jury of the time would not convict a Protestant on charges brought forward by a Catholic. Curran, who had a passion for lost causes, represented the priest and won over the jury by setting aside the issue of religion. The jury awarded Curran's client 30 guineas. Doneraile challenged Curran to a duel, in which Doneraile fired and missed. Curran declined to fire.