Comptroller-General v Pharm-a-Care  HCA 2
Tariff classification under treaty items copied into domestic law can be complicated4. Were vita-gummies free of duty as ‘medicaments … containing vitamins’?5 The English version of the treaty (our law) contains within Note 1(a) a general exclusion for ‘foods or beverages’ (absent in the French version).
Both texts are ‘equally authoritative’, however, and each treaty term is presumed to have the same meaning in each text. A meaning should be sought which gives effect to all treaty terms as used in each text6. Comparison of the texts meant reading down the general exclusion in Note 1(a) 7. Vita-gummies were not excluded and were therefore free of duty.
This principle is from Episode 58 of interpretation NOW!
4 Harmonized System Convention  ATS 30.
5 Item 3004.50.00 in Ch 30 of Section VI in S3 to the Customs Tariff Act 1995.
6 Eiser  FCA 157 (at ), cf Art 33 of the Vienna Convention.
7 This interpretive technique dates back at least to the time of Augustine.