At the end of Act III of The Crucible Reverend Hale quits the court. This action surprises the audience and shows us the changes that have occurred in his character.
I denounce these proceedings, I quit this court!
When Hale came to Salem in Act I, he came thinking he was coming to save the town, and its children, from a terrible witch outbreak. As he says in Act IV "I came into this village like a bridegroom to his beloved, bearing gifts of high religion..." Hale comes with his knowledge about the supernatural world, but without thinking the girls may be lying.
By Act III, the trail has taken over the town. Highly respectable women are accused (Rebecca, Martha, and Elizabeth). When Proctor comes to the court with proof (a signed deposition and Mary Warren's testimony) Hale is horrified that the courts will not let him present his case with a lawyer.
In God's name sir, stop here; send him home and let him come again with a lawyer-
Hale realizes that the courts are not interested in the truth. They want to believe the trails are true and that the girls are not lying. If they change their minds now, they'll be admitting they're wrong and have wrongly convicted innocent people.
When he realizes that the courts are not fair; he quits the court.
Reverend Hale quits the court and leaves Salem at the end of Act Three because his conscience will not permit him to participate in these trials. He has come to understand that the court is corrupt, that the girls are lying, and that innocent people are being convicted of witchcraft, a crime they have not committed, and condemned to hang. Further, anyone who opposes the trials is believed, by the magistrates and Reverend Parris, to be guilty themselves.
At the end of Act Two, John Proctor calls Reverend Hale Pontius Pilate, implying that Hale, rather than standing up to injustice, simply "washes his hands" of the corruption he witnesses. In a way, then, Proctor is right. Hale makes a few attempts to intervene on Proctor's and Giles Corey's behalf in Act Three, but when his pleas for justice are dismissed by Deputy Governor Danforth, he discontinues his objections and walks away. Later, his conscience demands that he return and try to help those convicted, but it is too late.