Trial by jury,Who an Why decided the # of 12 ?

Answer 1

It's not a fixed number.

Each court system has its own number, usually between 6 and 12, and its own rules on whether they must be unanimous (always for criminal trials) or how many of the number counts as enough (for civil trials).

The number is set by the Legislature of the jurisdiction.

The number 12 is historical, and comes from traditions of Old English common law.

Answer 2

they trew the dice, and two sixes came up./