A distinct but similar provision created a presumption in favour of the act's mandatory publication ban on the young person's identity being waived if the accused was convicted of certain violent offences unless the youth could convince the court to retain it.

B tried to apply for a youth sentence but was opposed by the crown, B challenged the constitutionality of the presumptive offence regime arguing that it imposed an impermissible reverse onus on the accused.

Not only because of the reverse onus, which infringed the established principle that the crown has the burden of proving aggravating factors, as a component of substantive presumption of innocence.

In recognizing the new principle, Abella J reviewed the long tradition of the Canadian justice system treating youth and adult accused differently.

She also noted it was widely acknowledged that age plays a role in decision-making capacity and moral development, and Canadian courts had long taken notice of that fact.

Overall, Abella held that there was widespread societal consensus that the presumption of diminished moral blameworthiness was fundamental to the fair operation of the legal system.

Ultimately, Abella J held that the presumption of diminished moral blameworthiness for young persons was the principle of fundamental justice, flowing from their heightened vulnerability, lower maturity, and reduced capacity for judgement.