Unfortunately, justice and law are not particularly connected in The Crucible, by Arthur Miller. In fact, what the law does and requires has little to do with justice in this story, which is one cause of the tragedy which happened in Salem in the 1690s.
First, in Salem the accusers are always right. It is clear that Thomas Putnam and his wife were making all manner of accusations (or prompting others to do so) for their own spiteful, greedy desires. Abigail Williams wanted nothing more than to get rid of the woman she saw as her rival (Elizabeth), and the other girls followed her because they did not want to get in trouble. In this courtroom, the accused may get questioned, but the accusers are always right. The judges even eat dinner with the accusers. Everyone (except the judges) comes to understand that these trials are not about justice at all but about punishing the accused and removing the blight (sin) of witchcraft from the town.
Second, at least one of the judges cared more about his reputation and pride than he did about justice. Every statement which was contrary to the girls' testimony was immediately labeled as "an attack against the court" by Judge Danforth. He capriciously decides when he wants these court proceedings to follow proper procedures and when he does not.
When Giles Cory wants to submit evidence, Danforth says, "Then let him submit his evidence in proper affidavit. You are certainly aware of our procedure here...." Francis Nurse, a few lines later, makes a quiet complaint that he has brought evidence to the court for the past few days but have been unable to present it. Nurse says, "We are desperate, sir; we come here three days now and cannot be heard." Justice and the law were less important to Danforth than his own will and wishes, and court procedures are followed only according to the whim of the judges.
In the final act, when Reverend Hale begs Danforth to postpone the hangings, Danforth is adamant that he cannot look as if he is faltering in any way. Even when he learns that Abigail has absconded, Danforth refuses to bend.
Third, the justice system is Salem is was based on religious belief more than the law. Danforth says:
Do you know, Mister Proctor, that the entire contention of the State in these trials is that the voice of Heaven is speaking through the children?
This means the evidence is largely supernatural and cannot be countered with reason or hard evidence. It is impossible for justice to prevail when the only evidence of witchcraft is irrefutable because it is unknowable by any but the accusers. Danforth refuses to postpone any hangings because he has been called by God to rid Salem of sin. "While I speak God’s law, I will not crack its voice with whimpering."
The only people in Salem who have to prove their case are the people who disagree with the accusers; this is antithetical to a true justice system in which the accused are innocent until proven guilty. There may be a form of law in Salem, but there is no justice.