The Court of Appeal has rejected a bid by the corruption watchdog to reinstate corrupt conduct findings against one of the targets of its landmark investigation into the Obeid family's $30 million coal deal.

In July last year former RAMS Home Loans founder John Kinghorn became the first person in more than 20 years to be cleared of corrupt conduct in NSW after the Supreme Court quashed ICAC's finding against him.

John Kinghorn arriving at the ICAC hearing in Castlereagh Street, Sydney, in December 2012. Credit:Nic Walker

ICAC sought to appeal the ruling but later agreed to drop the case after a High Court ruling in April made its findings against Mr Kinghorn and others untenable. That ruling, relating to ICAC's ill-fated attempt to investigate Crown Prosecutor Margaret Cunneen SC, substantially narrowed the scope of ICAC's powers as they had been interpreted by the agency.