There are no exhaustive or rigid rules of practice or criteria governing the grant of leave to appeal: Adam P Brown Male Fashions Pty Ltd v Philip Morris Inc  HCA 39; 148 CLR 170. However, it has been consistently stated that leave should only be granted where there are substantial reasons that call for appellate review: Johnson Tiles Pty Ltd v Esso Australia Pty Ltd  FCA 1572; 104 FCR 564, and, in particular, where there is an error of principle, a matter of public importance, or injustice which is reasonably clear in the sense of going beyond what is merely arguable: see Darrell Lea (Vic) Pty Ltd v Union Assurance Society of Australia Ltd  VR 401; Niemann v Electronic Industries Ltd  VR 431; BHP Petroleum Pty Ltd v Oil Basins Ltd VR 756; Carolan v AMF Bowling Pty Ltdt/as Bennetts Green Bowl  NSWCA 69; Minogue v Williams (2000) 60 ALD 366; Jaycar Pty Limited v Lombardo  NSWCA 284; Be Financial Pty Ltd as Trustee for Be Financial Operations Trust v Das  NSWCA 164; Clarke v State of New South Wales  NSWCA 27. In Collier v Lancer (No 2)  NSWCA 186, the Court reiterated that appellate review will be warranted where, for instance “there is an error of principle which, if uncorrected, will result in substantial injustice”.
Another consideration in determining whether to grant leave is the sum in issue in the proposed appeal: Dunn v Ross Lamb Motors (1978) 1 NSWLR 26. Although there is no minimum amount specified in the rules of court below which leave will not be granted, the Court has refused leave in matters because of the small amount involved, such as where it was considered the grant of leave was not warranted having regard to the appropriate allocation of court resources and the disproportionate costs to the parties: see Wilson v Tetley  NSWCA 124; Zelden Sewell Henamast Pty Ltd  NSWCA 56; Jaycar Pty Ltd v Lombardo. Accordingly, whilst the mere fact that a small amount is in issue will not necessarily disentitle a person to a grant of leave, having regard to the case management principles enshrined in the Civil Procedure Act, it will nonetheless be a relevant factor and in an appropriate case may be decisive.