C was convicted in Victoria of involving another in production of child abuse material – s 51B of the Crimes Act 1958. While in SA, he phoned someone in Victoria giving step-by-step instructions about what was to occur. Related provisions had extraterritorial effect, but not s 51B. C argued this meant his SA conduct was not caught because positive extension of other provisions implied no extension of s 51B11.
The court (at ) said expressio unius must be applied with care12. Differences between provisions may be deliberate or the product of ‘inadvertence or accident’13. The latter was likely here, due to the ‘base position’ of physical contact under the statute.
This principle is from Episode 94 of interpretation NOW!
11 expressio unius est exclusio alterius – Spence  HCA 15 (at ).
13 Colquhoun (1888) 21 QBD 52 (at 65), cf Pearce 9th ed (at [4.43-4.45]).