'Ignorance of the law does not excuse him'


The above quote is an ancient proverb and a principle in law.


It means that just because a person does not know the law, does not mean that he/she cannot be held accountable to the law.


In other words, just because someone is ignorant of the law is no excuse and will not be a defence.


Nevertheless, there is a defence whereby you can be acquitted (ie: not guilty), if you held an honest and reasonable belief you were not breaking the law.


A word of caution though, it MUST be honest and reasonable belief as to a FACT not as to the law.


Distinguishing between a mistake of fact (which will satisfy a defence) and a mistake of law (which will be no excuse) can be tricky.


The defence is called HONEST & REASONABLE MISTAKE OF FACT, abbreviated to HRMF.


Commonly it is seen in driving offences whereby a person was under the honest, reasonable but mistaken belief of fact they still had a valid licence to drive. For instance, because they did not receive the RMS disqualification/suspension letter.


The honest & reasonable mistake of fact defence has also been used when a person is driving under the influence of say cannabis, but mistaking believe it was all out of their system when they were driving 5 days later.


The two (2) cases below demonstrate the defence in action: -

  1. Ostrowski v Palmer is a western Australia fishing case, where Mr Palmer attempted to use the defence of honest & reasonable mistake of fact when he was caught fishing in illegal waters. Mr Palmer had lowered rock-lobster pots in waters where such actions were illegal.


As his defence to honest & reasonable mistake of fact he relied on the advice he received from the fisheries that those waters were not illegal. However, this was a mistake of law – not knowing the waters were illegal and thus was no excuse. This is different to knowing the waters are illegal but thinking he had permission. The defence failed as his mistake was a mistake of law not a mistake of fact.



  1. Another example is a driving whilst disqualified case of EL Hassan v DPP. Mr El Hassan was stopped by police whilst driving his motor vehicle and upon a check of his licence was found to have been suspended, thus he was caught driving whilst disqualified. At Court Mr El Hassan relied on the defence of honest & reasonable mistake of fact, since he thought his licence was not suspended since he had already entered a payment plan with the RMS to pay his outstanding fines.


Interestingly this is a great use of an honest & reasonable mistake of fact defence – since he was not arguing he did not know he needed a valid driver’s licence to drive (being a mistake of law), but instead the fact that he thought he had a valid driver’s licence at the time of driving, as he had entered into a payment plan with the RMS (a mistake of fact).


However, unfortunately for Mr El Hassan the Court did not believe he held that honest and reasonable belief of fact since Mr El Hassan was in the Court opinion neither honest nor was the fact reasonable given his driving record, previous offending, and previous contact with the RMS.


If you or someone you know is facing a criminal charge and believe you may have held an honest & reasonable mistake of fact as to the circumstances. Please contact us at Rep-Revive Criminal & Employment Lawyers on 9198 1996, we offer a free initial consultation on all criminal matter.







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