In "The Crucible," why is Giles Corey expelled from court, not allowed to present his testimony, and arrested?

In the court, Corey accused Putnam of trying to take his and George Jacobs' land. In the middle of this, John Proctor presents a petition from different townspeople that supports Elizabeth, Rebecca Nurse and Martha Corey. Danforth accused Proctor of trying to undermine the authority of the court.

At that point, Danforth orders the arrest of all the people who signed the petition. Then Abigail tries to distract the court by saying she sees a big bird representing the spirit of Mary Warren. Proctor has had enough and admits to adultery with Abigail, but when Elizabeth is brought in, she denies that affair between her husband and Abigail in order to protect her husband. After this, Danforth has had enough and orders both Proctor and Corey arrested. 

It is obvious at this point that Danforth is more interested in protecting the court and his own reputation than finding the truth. This can be seen by Reverend Hale's reaction. He criticizes the trials and leaves the court.