Ms Momcilovic was convicted of drug trafficking, based on the fact that she was the occupant of the premises at which the drugs in question were found and that those drugs were of a traffickable quantity. In these circumstances, section 5 of the Drugs, Poisons and Controlled Substances Act 1981 placed the onus on Ms Momcilovic to prove her innocence once it had been established she was occupying the premises on which the drugs were found.
It was argued that the reverse onus provision infringed her right to the presumption of innocence under s 25(1) of the Charter. Ms Momcilovic appealed against the conviction. One of the grounds was that section 32 of the Charter required section 5 of the Act be interpreted as placing only an evidentiary burden on an accused.
The Commission's intervened to make submissions on the effect of section 32 of the Charter on the interpretation of section 5 of the Drugs, Poisons and Controlled Substances Act 1981. The Court had previously held that section 5 imposed a legal burden of proof on the person to whom it applies. That burden is discharged by proof on the balance of probabilities that the person was not in possession of the relevant substance. The Commission submitted that section 32 of the Charter requires the Court to depart from existing authority and to interpret section 5 as imposing only an evidential burden.
The Court of Appeal held that the reverse onus established by section 5 of the Act was a breach of the right to be presumed innocent in section 25 of the Charter. The Court held that it was not "possible" to interpret this provision consistently with the right to the presumption of innocence and made a declaration of incompatibility under section 36 of the Charter.
This decision was appealed to the High Court of Australia. See Momcilovic v The Queen (High Court) - Charter intervention - Sep 2011.