A Kentish jury, hang half and save half. [ Proverb ]

He that wrongs his friend
Wrongs himself more, and ever bears about
A silent court of justice in his breast,
Himself the judge and jury, and himself
The prisoner at the bar, ever condemned. [ Alfred Tennyson ]

A fox should not be of the jury at a goose's trial. [ Proverb ]

Be neither too early in the fashion, nor too long out of it, nor too precisely in it; what custom hath civilized is become decent, till then ridiculous; where the eye is the jury thy apparel is the evidence. [ Quarles ]