Doli incapax (Latin for ‘incapable of deceit’) is the legal doctrine that children can’t commit a crime because they don’t know the difference between right and wrong, and so can’t form the mens rea (or criminal intent) required to prove guilt.
The doctrine can operate in two ways.
First, it can presume that children between specified ages are doli incapax. The common law on this point considered that the prosecution must prove the child knew their acts were ‘seriously wrong’ to overcome the presumption. That would mean the child was then considered doli capax.
Second, the doctrine may operate as a defence, if the child proved in fact they didn’t know right from wrong and so couldn’t commit a crime alleged against them. (The meaning of child varies over time and jurisdiction.) The child would not need to rely on the defence unless the prosecution first rebutted the presumption.
The doctrine was accepted around the 18th century. At that time, all offences were indictable and divided only into felonies (punishable by death) and misdemeanours (which weren’t punishable by death). There were no strict or absolute liability offences then, and no summary courts. There doesn’t seem to be any jurisprudence on doli incapax and offences that don’t require a mental element. Does this mean children of any age can commit strict and absolute-liability offences? Perhaps there could have been an argument about this under the common law, but I think legislation removed any possibility of that here.
In ALH the Victorian Court of Appeal also thought there were problems were the doctrine, but unlike the English House of Lords, didn’t argue for its abolition. Instead, Victoria adopted a different approach: proving the charge alleged against the child could also prove knowledge it was seriously wrong.
That results in a sliding scale of offence seriousness versus the age of the child. The more serious the offence, the more likely the child knew it was wrong. The older the child, the less serious the offence need be for the child to know it was wrong. The way I think that works in practice is like this…
Consider 10-year-old Timmy. He accidentally kicks his football into the back yard of old Mrs Gruff, the terror of all the kids in the neighbourhood. He knows she’ll scold him if he asks to get his ball, so he jumps the back fence to get it. She calls the police, and they find Timmy in the back yard. Potentially, he trespassed in her backyard. Would most 10-year-olds realise going into someone’s backyard to get their footy without permission might be a criminal offence? I reckon they probably wouldn’t. They might know they should ask for permission first — but that’s not the same thing. Rebutting the presumption of doli incapax will be difficult in this example.
Let’s imagine Timmy was throwing rocks at and breaking Mrs Gruff’s windows. A more serious potential offence. So, it’s more likely — even at 10-years — that Timmy knows it’s ‘seriously wrong’ to do it. In that case, rebutting the presumption won’t be as difficult, and the nature of the offence itself (assuming it’s proved) tends to suggest Timmy knew it was wrong.
And if Timmy instead decided to burn Mrs Gruff’s house down, I think most of us would expect him to know that is ‘seriously wrong’ — a criminal offence.
At the other end of the scale, a 13-year-and-350-days-old child would be far more likely to know that trespassing is a criminal offence or ‘seriously wrong’. Though the prosecution would still need to establish that additional element, it would not be as difficult as for 10-year-old Timmy.