In Dubio Pro Reo and the Presumption of Innocence

In dubio pro reo is a Latin expression commonly used to describe
the principle that a person accused of a crime should receive the benefit
of a genuine doubt about guilt.

In the criminal law of England and Wales, the underlying principle is more
precisely expressed through the presumption of innocence,
the prosecution’s burden of proof, and the requirement that the prosecution
make the tribunal sure of the defendant’s guilt.

The Prosecution Carries the Burden

The foundational English authority is
Woolmington v Director of Public Prosecutions [1935] AC 462.
The House of Lords described the prosecution’s duty to prove the defendant’s
guilt as the “golden thread” running through English criminal law, subject
to recognised exceptions.

The defendant does not ordinarily have to prove innocence. Where, after
considering the whole of the evidence, a reasonable doubt remains as to
an essential element of guilt, the prosecution has failed to discharge
its burden.

“Sure” — Not Merely Possible or Plausible

Modern judicial directions in England and Wales ordinarily express the
criminal standard by asking whether the prosecution has made the tribunal
sure of the defendant’s guilt.

The Judicial College states that, where the burden rests on the prosecution,
the prosecution must prove that the defendant is guilty and must make the
jury sure of that guilt. If the jury is not sure, the appropriate verdict
is not guilty.

The familiar expression “beyond reasonable doubt” conveys the same standard,
but the modern judicial direction generally uses the language of being
“sure”.

What Happens When the Evidence Does Not Fit?

Criminal proof may depend upon a chain of factual propositions. If one
proposition requires a physical mechanism, chronology or spatial arrangement
that is not supported by the evidence, the problem is not solved merely by
assuming that the mechanism occurred.

The evidential question becomes whether the prosecution has established the
necessary facts and whether the conclusions drawn from them are sufficiently
supported to make the tribunal sure of guilt.

A physical contradiction therefore does not itself produce an acquittal.
Its legal significance depends upon what proposition it undermines and whether,
after the evidence as a whole has been considered, the prosecution has still
discharged its burden.

The Defendant Does Not Carry the Ordinary Burden of Proving Innocence

Article 6(2) of the European Convention on Human Rights provides that
everyone charged with a criminal offence shall be presumed innocent until
proved guilty according to law. In the United Kingdom, this protection is
given effect through the Human Rights Act 1998.

The common-law principle in Woolmington complements this protection:
subject to recognised exceptions, the prosecution must prove the defendant’s
guilt rather than requiring the defendant to establish innocence.

When Doubt Becomes Legally Significant

• What element of the offence must the prosecution prove?
• What evidence is relied upon to establish that element?
• Does the evidence support the necessary factual inference?
• Does a physical, chronological or scientific inconsistency undermine that inference?
• Are competing explanations supported by evidence or merely speculative?
• After considering the evidence as a whole, has the prosecution made the tribunal sure of guilt?

Doubt is not the same as speculation.

The criminal standard does not require the fact-finder to entertain every
imaginable alternative or to reject evidence merely because another
possibility can be invented.

The relevant question is whether, having considered the evidence and the
reasonable inferences properly available from it, the prosecution has
established guilt to the required criminal standard.

This page presents an academic framework for analysing criminal proof.
It does not determine the factual truth of any individual case.