Where an interlocutory judgment is not discretionary and not in a matter of practice and procedure but effectively determines substantive rights (such as a refusal of leave to commence proceedings under s 155 of the ICAC Act), the applicable test for leave to appeal is not the Niemann test (sufficient doubt plus substantial injustice) but rather the Ex parte Bucknell test: a prima facie case for leave exists, and leave should be granted unless the court forms a clear opinion adverse to the success of the proposed appeal.
The full text is available to signed-in members, including the 1 later case that cites this judgment.