The case must be proven beyond a reasonable doubt.
Generally the defendant's word, so far as the jury can see, is as good as his accuser's.

If there are other witnesses it is usually not difficult, and certainly not impossible, to show that they have poor eyesight, bad memories, or are undesirable citizens in general.
The criminal lawyer learns in his cradle never to admit anything.
By getting constant adjournments he wears out the People's witnesses, induces others to stay away, and when the case finally comes to trial has only the naked accusation of the complainant to disprove.
Or, to put it in more technically correct fashion, the complainant has only his own word wherewith to establish his case beyond a reasonable doubt.

A bold contradiction is often so startling that it throws confusion into the enemy's camp.
I once defended a worthy gentleman named Cohen on a charge of perjury, alleged to have been committed by him in a civil case in which he, as defendant, denied that he had ever ordered a set of stable plans from a certain architect.

The latter was a young man of very small practice who had an office but no clerks or draughtsmen.
He certainly believed with the utmost honesty that my client had come to his office, engaged him to design a stable, and approved an elaborate set of plans that he had drawn.

When it came to paying for them Mr.Cohen declined.