In Act III John Proctor, Francis Nurse, and Giles Corey come to the court with what they think is strong enough evidence to prove that the girls are frauds. However, this point the court has already executed several convicted witches, and countless more have been imprisoned. Because of this the court is not open to hearing testimony that goes against their rulings.
Putnam is using the case as an attempt to gain land and power. Hale warns the courts to be careful with his testimony. He realizes Putnam is using the trial as a personal opportunity and not trying to save the girls from their affliction with witches.