I have no knowledge of the law, but my lay understanding was that English law has two verdicts, guilty and not guilty. In Scottish law, a form of Roman law, there are three verdicts, guilty, not proven, and innocent. The Romans themselves said either ignoramus 'we do not know' or non liquet 'it is not clear' for the middle term -- I don't know which of those was the correct legal term.

I would have thought that the law of Australia, NZ, 49 US states, and 9 Canadian provinces was English common law: the exceptions being the Roman law of Quebec and Louisiana.

Repeating the disclaimer, this was my purely linguistic and unconfirmed udnerstanding of the difference.