Standard of Proof
The evidence overall must create a case where there is no reasonable doubt as to the guilt of the defendant. This principle does not relate to the reliability, meaning or weight of each individual item of evidence, but rather the certainty of guilt created by the whole case, both sides taken together. Where there is a realistic alternative explanation for the alleged crime, then this constitutes reasonable doubt. The police must investigate deeply enough to eliminate any question pertinent enough to cast doubt on the case as a whole. The prosecution also must be careful to apply as realistic an interpretation to the facts as possible and to maintain complete circumspection, to avoid presenting a fatally flawed case. Where facts arise which, given the other facts in the case, point to non-guilt, then this may amount to a reason not to proceed with a trial. A classic authority on this is found in Woolmington where Lord Sankey stated:
If, at the end of, and on the whole of the case, there is reasonable doubt, created by the evidence given by either the prosecution or the prisoner as to whether the prisoner killed the deceased with malicious intention, the prosecution has not made out the case and the prisoner is entitled to acquittal. No matter what the charge or where the trial, the principle that the prosecution must prove the guilt of the prisoner is part of the common law of England and no attempt to whittle it down can be entertained.
In saying “…the prosecution must prove the guilt of the prisoner…” his Lordship’s intent can be distinguished from the questionable nature of a civil law outcome in which in spite of a remedy being given, a question remains based on the fact that a party to a civil matter will succeed over the other if their case is only slightly stronger, as long as it holds together on its own.
Furthermore, it is the position in Australia, that no direction is to be given to the jury as to the meaning of reasonable doubt. What constitutes a reasonable doubt is the normal, everyday meaning as understood by any normal person.
 Woolmington v Director of Public Prosecutions  AC 426, 481-2.