The Law of Moses was meant to be a protection for the weak.
It included trial law to protect the accused. Under the Law of Moses the accuser had a lot of responsibility.
The only person who could bring charges against another person was a direct witness of the crime. Two or three witnesses were required. (A woman could not be a witness because she was too easily influenced by the men in her life.) With capital crimes, the witnesses who brought the charges had to explain what they saw, and then they had to cast the first stones to execute the accused. If their testimony was false, they themselves would be killed.
The woman who was brought to Jesus and accused of adultery presented an odd situation. Adultery was a capital crime, punishable by death. She should have been taken to the regional religious court or to the Sanhedrin comprised of high priests, since this happened in Jerusalem. She was brought to Jesus by the Pharisees to test Jesus’ response. Jesus didn’t have the authority under Jewish law to judge her (even though He is the judge of heaven and earth).
The Pharisees surely hoped He would judge her, and then they could accuse Him of a crime against Mosaic law. The way Jesus handled the situation again showed His divine genius. He simply said, “Let him who is without sin cast the first stone at her.” Either her accusers were false accusers or they came to an awareness of their own hidden sins. After they departed, Jesus forgave her privately.