The federal/ACT codes have a codified form of the common law (SA, really) defence of act of another. It& #39;s little used and rarely succeeds.

Some incompetent round-the-world yachters (facing forfeiture of their yacht) unsuccessfully raised it last year: http://classic.austlii.edu.au/au/cases/cth/FCA/2018/1620.html.">https://classic.austlii.edu.au/au/cases/...

But I& #39;ve just noticed that it succeeded in two ACT cases:
- a restaurant whose customers ended up with salmonella poisoning successfully raised it because there was no way to guard against the odd dodgy egg: https://courts.act.gov.au/magistrates/decisions/stedman-v-zeffirelli-pizza-restaurant.">https://courts.act.gov.au/magistrat...

- a driver who tested positive to meth won her appeal because the magistrate had barred her from raising the defence, given her evidence that she no longer smoked meth and must have ingested passively at a party or somewhere: http://classic.austlii.edu.au/au/cases/act/ACTSC/2015/350.html.">https://classic.austlii.edu.au/au/cases/...

(I guess she couldn& #39;t raise honest and reasonable mistake of fact because her story is that she never gave the possibility of meth in her saliva/blood any thought. Here& #39;s a similar Qld case noting that the defence of act of another isn& #39;t available there: http://classic.austlii.edu.au/au/cases/qld/QMC/2016/27.html.)">https://classic.austlii.edu.au/au/cases/...

But mistake of fact was successfully raised in a cannabis driving case in the NSW Local Court: https://www.caselaw.nsw.gov.au/decision/57577e01e4b058596cb9c11e.">https://www.caselaw.nsw.gov.au/decision/... The difference there was that the D said he smoked a week earlier but thought the cannabis would be out of his body by now.

In a later case (before the same magistrate), there was conflicting expert evidence of how long cannabis stays in the body, with the court accepting the D expert: https://www.caselaw.nsw.gov.au/decision/58e59e71e4b0e71e17f58890.

But">https://www.caselaw.nsw.gov.au/decision/... the defence failed because D admitted thinking he may have some cannabis in his blood.

The whole line of cases raises some really interesting issues with enforcing some crimes - and there seem to be good policy arguments on each side.

I haven& #39;t seen the issue coming up in Victoria though, perhaps because our drink/drug-driving laws are so nasty?