Beyond reasonable doubt is the standard of evidence required to validate a criminal conviction in most adversarial legal systems.
Generally the prosecution bears the burden of proof and is required to prove their version of events to this standard. This means that the proposition being presented by the prosecution must be proven to the extent that there could be no "reasonable doubt" in the mind of a "reasonable person" that the defendant is guilty. There can still be a doubt, but only to the extent that it would not affect a reasonable person's belief regarding whether or not the defendant is guilty. "The shadow of a doubt" is sometimes used interchangeably with reasonable doubt, but this extends beyond the latter, to the extent that it may be considered an impossible standard. Reasonable doubt is therefore used.
If doubt does affect a "reasonable person's" belief that the defendant is guilty, the jury is not satisfied beyond "reasonable doubt". The precise meaning of words such as "reasonable" and "doubt" are usually defined within jurisprudence of the applicable country.
Famous quotes containing the words reasonable and/or doubt:
“How can anyone be interested in war?—that glorious pursuit of annihilation with its ceremonious bellowings and trumpetings over the mangling of human bones and muscles and organs and eyes, its inconceivable agonies which could have been prevented by a few well- chosen, reasonable words. How, why, did this unnecessary business begin? Why does anyone want to read about it—this redundant human madness which men accept as inevitable?”
—Margaret Anderson (1886–1973)
“If ever I should condescend to prose,
I’ll write poetical commandments, which
Shall supersede beyond all doubt all those
That went before; in these I shall enrich
My text with many things that no one knows,
And carry precept to the highest pitch:
I’ll call the work ‘Longinus o’er a Bottle,
Or, Every Poet his own Aristotle.’”
—George Gordon Noel Byron (1788–1824)