Mining mogul and former Cascade Coal director Travers Duncan has applied to the High Court to strike down NSW legislation that validated findings made against him made by the corruption watchdog, on the basis that it is constitutionally invalid.

The appeal may cast doubt on the validity of laws rushed through Parliament by the Baird government on May 6, to validate any past corruption findings by the Independent Commission Against Corruption that were put into question by the High Court's decision in Cunneen.