The complete phrase is "guilty beyond peradventure (= chance) of doubt."
At the very beginning of this subject, you must thoroughly understand that it means the doubt of a reasonable man who is earnestly seeking the truth. It does not mean the doubt of a man who is earnestly looking for doubts. It means such a doubt that exists in the mind of a juror after there has been, on his part, an honest and conscientious effort to ascertain the truth. It does not mean a doubt beyond all peradventure. Neither does it mean beyond all imaginary or possible doubt, because everything relating to human affairs and human evidence is open to some possible or imaginary doubt.
I like it.
BTW, good point, thanks.