Reverend Hale's character helps to show that those who wash their hands of responsibility of wrongdoing, so to speak, are just as responsible as those who commit the wrongdoing. Tellingly, at the end of Act Two, as Elizabeth Proctor is being arrested on suspicion of witchcraft, John Proctor, her husband, calls Hale "Pontius Pilate" and says that "God will not let [Hale] wash his hands of this!" In other words, John feels that Hale will not be able to rid himself of his responsibility to intervene by simply refusing to do so one way or the other. Hale has said, again and again, that the people of Salem can rely on the justice of the court. He claims that he has seen signs of witchcraft here, himself, but that if those arrested are innocent, then the court will find them to be so and send them safely home. During Act Three, Hale tries to assist John in bringing his evidence before the court, and it is obvious that he now has grave doubts about the guilt of those convicted, and yet, when Deputy Governor Danforth will not listen, Hale just quits the court and leaves Salem. Rather than continue to fight against the injustice he sees, he simply walks away, and by the time he comes back, it is too late.
When Hale returns in Act Four, he now realizes his own responsibility in the trials and in the executions of innocent people. He tries to reason with Danforth but to no avail. He now feels that there is "blood on [his] head," meaning that he bears some guilt for the hangings which have occurred and those that will occur. His character helps to illuminate the theme that doing nothing to stop injustice is as bad as participating in that injustice oneself.