Take a look at all of the people that are "safe" in this play, versus all of the people that get accused. Abigail, a selfish, conniving, threatening, violent and manipulative girl, is reigning queen. She can do or say whatever she wants, and people believe her. Even though she was one of the few that could possibly be considered guilty of conjuring and casting spells, she is the one that gets off scot free. She is plainly evil, and yet the courts protect her. Even when she is openly accused of adultery, Danforth stages a situation that works out in her favor, and makes her accuser look like a liar.
Then, take Giles Corey, an honest, old man who comes to the courts with bold evidence that a greedy, land-grubbing Putnam is "killing his neighbors for their land." Instead of believing Corey, the courts cast suspicion on his testimony and come up with ridiculous excuses for not believing his word, and arrest HIM instead of the obviously wicked man, Putnam. Here we have Putnam, who is telling his daughter who to accuse of witchcraft so that he can grab their land, and he is getting away with it, clean and free. Putnam is safe. But a truly honest and good man like Giles Corey comes to the courts just to try to shed some light and provide evidence, and he ends up arrested, and in the end, killed.
When Mary Warren is trying to be good and tell the truth about the girls being false, the courts examine her, doubt her, and play mean tricks on her to try to discredit her testimony. However, when she turns and starts behaving badly and wickedly, pretending John bewitched her, they believe her immediately; they don't question her once. She is safe when being evil, and in danger when being good.
Those are just a few instances. Danforth disguises the illogical and wicked designs of the courts behind the pretty front of being "fair" to all, and behind the supposed innocence of good people. It's all just a weak excuse, disproved over and over as good people are taken down, one by one. I hope that those thoughts helped; good luck!