What legal right is protected by the presumption of innocence?

The presumption of innocence is the legal principle that a person charged with an offence is innocent until proven guilty by the Crown beyond a reasonable doubt. In Canada the principle is constitutionalised in section 11(d) of the Canadian Charter of Rights and Freedoms, which guarantees that 'any person charged with an offence has the right to be presumed innocent until proven guilty according to law in a fair and public hearing by an independent and impartial tribunal'.

Section 11(d) requires that the Crown bear the burden of proof, that the standard of proof be beyond a reasonable doubt, and that the accused be tried in an independent and impartial court. The Supreme Court of Canada applied this framework in R. v. Oakes (1986), striking down the reverse onus in section 8 of the Narcotic Control Act and creating the Oakes test that has since been used to evaluate every Charter limit. The standard of proof beyond a reasonable doubt was re-affirmed in R. v. Lifchus (1997), which provided model jury instructions to all Canadian criminal trials.

The presumption of innocence is older than the Charter. It traces to English common law, was articulated in Woolmington v. Director of Public Prosecutions (1935) by the House of Lords as the 'golden thread' of criminal law, and was inherited by Canada through the Constitution Act, 1867. Section 6(1)(a) of the Canadian Bill of Rights of 1960 also protected the presumption, though the Bill of Rights was a federal statute rather than constitutional law and applied only to federal legislation.

The presumption is reinforced by other Charter sections. Section 7 protects life, liberty, and security of the person and the right not to be deprived thereof except in accordance with the principles of fundamental justice. Sections 8 through 14 protect against unreasonable search and seizure, arbitrary detention, the right to counsel, the right to a trial within a reasonable time (R. v. Jordan, 2016, set ceilings of 18 and 30 months), the right against self-incrimination, and the right to an interpreter. Together these sections form the constitutional framework that protects every person in Canada accused of an offence.