The late 1600s saw the advent of a more modern adversarial system in England and its American colonies. Juries took a more neutral stance, and appellate review, previously unavailable, became possible in some cases.

When was the adversarial system start?

Some academics place the beginning of the adversary system in the 18th century, when lawyers began to get control of the criminal process, but lawyers had control of the civil process much earlier. If you control the evidence, you control the money.

Why was the adversarial system created?

In the eighteenth century, some courts allowed that prohibition to be lifted by permitting defense counsel to cross-examine some witnesses. The standard history concludes that this presence of defense counsel formed the foundation of the adversary system.