In act three of The Crucible by Arthur Miller, Elizabeth Proctor finds herself in an awful predicament, and none of it is her doing.
Elizabeth's husband John had an affair with their servant girl, Abigail Williams. Elizabeth was not certain it was happening, but she sent Abigail away and John confessed. Since then things have been quite strained between the Proctors, of course. John feels guilty because he is a man of good character despite this failing. He also feels as if Elizabeth is watching him too closely, though that seems more about his own guilt than anything Elizabeth is actually doing.
When the witch trials begin to spin out of control and Abigail accuses Elizabeth of witchcraft, John knows he has to tell the court what Abigail told him on the day the cries of witchcraft began: none of this is real and the girls are just pretending.
In court, John is forced to admit that he had an affair with Abigail. It is a shameful moment for him. When Abigail denies it, John points out that he has just ruined his good name, and the only thing that would prompt that is his need to tell the truth. Judge Danforth does not believe him and needs further proof.
Proctor tells the judge that Elizabeth never lies.
In her life, sir, she have never lied. There are them that cannot sing, and them that cannot weep - my wife cannot lie. I have paid much to learn it, sir.
Danforth sends for Elizabeth, and this is where her troubles begin. When she enters the courtroom, both Abigail and her husband are facing the front of the room; all she can see is their backs. The judge asks her several things about John and Abigail, and it is clear to Elizabeth that her husband is about to be called out as an adulterer. She loves her husband and does not want that to happen to him, so she goes against her own character in this moment.
Danforth: Look at me! To your own knowledge, has John Proctor ever committed the crime of lechery? In a crisis of indecision she cannot speak.
Danforth: Answer my question! Is your husband a lecher!
Elizabeth, faintly: No, sir.
Danforth: Remove her, Marshal.
Proctor: Elizabeth, tell the truth!
Danforth: She has spoken. Remove her!
Proctor, crying out: Elizabeth, I have confessed it!
Elizabeth: Oh, God! The door closes behind her.
The irony of this exchange is that Elizabeth always tells the truth; however, the one time she lies to save someone she loves, it backfires on her. If she had remained true to herself, she would have told the truth, saved John, condemned Abigail, ended the trials, and lived the rest of her life with her husband. Instead, she does what she thinks is best and lies, and now all is lost.