Principles applicable in determining whether contracts are unenforceable for statutory illegality discussed in Barker v Midstyle Nominees Pty Ltd [2014] WASCA 75 at [36] and [37] as follows:
[36] When the making or performance of a contract is expressly or impliedly prohibited by statute, and a contract is made or performed in contravention of the prohibition, the contravention may operate as a defence to the right that a party to the contract would otherwise have to enforce it.
[37] A contract may be unenforceable for statutory illegality where:
  • (a) the statute expressly prohibits, absolutely or conditionally, the making of the contract or the doing of an act essential to its formation (first category);
  • (b) the statute impliedly prohibits the making of the contract (for example, where the contract is to perform an act the performance of which is prohibited by the statute) (second category); or
  • (c) the statute does not expressly or impliedly prohibit the contract, but the courts treat the contract as unenforceable because it is associated with or furthers illegal purposes (third category).

See Miller v Miller [2011] HCA 9 ; (2011) 242 CLR 446 [26] (French CJ, Gummow, Hayne, Crennan, Kiefel & Bell JJ); Equuscorp Pty Ltd v Haxton [2012] HCA 7 ; (2012) 246 CLR 498; [23] (French CJ, Crennan & Kiefel JJ).