The presumption of innocence is at the heart of our criminal justice system. As a cornerstone of criminal law principles, the presumption of innocence guarantees a fair trial for all. By ensuring only those individuals who are found guilty will be punished, it protects the vulnerable individual from the awesome powers of the State. It is indeed a fundamental principle, constitutionally entrenched in our Charter, and an integral part of our rule of law.
As important as this principle is to our concept of justice, the presumption of innocence has become much more than a legal tool; it has become part of the fabric of our society. Today, every citizen is aware of the presumption of innocence in a criminal case. This principle has transcended the legal arena to become one of our society’s fundamental values. It is not only a value understood by all but it is part of our culture. It can be found in journalism, literature, movies, and television.
Yet, historically, according to academic scholars, the presumption of innocence was not a fundamental principle but a general rule of evidence used in civil cases. In a series of articles, George Fletcher, a well-known scholar now Cardoza Professor of Jurisprudence at Columbia Law School, maintained the presumption of innocence did not become part of the common law nomenclature until the mid-1800s.
In fact, the concept of the presumption arose from a series of civil cases in the early 1800s wherein the court applied the common sense evidentiary rule that a man (yes, this is the early 19th century) is presumed to fulfill his legal obligations. Thus, if a plaintiff is alleging the negative situation, that the defendant did not fulfill his legal obligation, then the plaintiff must prove otherwise. Only later, did this evidentiary rule apply to criminal case and then became, what we call, the presumption of innocence.
According to Fletcher, even the core concept of the burden of proof in a criminal case, which requires the Crown to prove guilt beyond a reasonable doubt developed separately from the presumption of innocence and only later, in the 1850s, did these two principles become connected. In the Commonwealth, the ultimate articulation of this connection is found in every first year law student's curriculum: the House of Lords case of Woolmington v. D.P.P from 1935. In this seminal case, Lord Sankey famously describes the presumption of innocence and the burden of proof in a criminal case, which is to prove the crime beyond a reasonable doubt, as the "golden thread...woven deep into the fabric of our law."
In the Oakes case, Chief Justice Dickson waxed eloquent on this dual concept and found the presumption of innocence essential to society as it "confirms our faith in humankind; it reflects our belief that individuals are decent and law‑abiding members of the community until proven otherwise." It was indeed the Charter which elevated and crystallized the presumption of innocence as the fundamental concept of our criminal justice system.