In Act III of Arthur Miller's The Crucible, does Mary Warren actually admit that she lied even when she knew innocent people would hang by her...

In Act III of Arthur Miller's The Crucible, Mary Warren does, indeed, admit to having lied before the court. Act III is occupied primarily by the proceedings, the outcome of which will result in the deaths of many innocent people. When Mary is again questioned regarding her role in the chain of events leading up to this point by Judge Thomas Danforth, the presiding judge during the trial, who has traveled to Salem for the sole purpose of purging this community from all traces of sorcery, she recants her earlier damning testimony:

Danforth: Then you tell me that you sat in my court, callously lying, when you knew that people would hang by your evidence?

She does not answer.

Danforth:  Answer me!

Mary Warren, almost inaudibly: I did, sir...

As with Abigail, but lacking Abigail's vindictiveness and guile, Mary Warren has trapped herself in a web of deceit from which she cannot escape. Having perjured herself earlier in the trial, she is now hard-pressed to be perceived as honest by a panel of men determined to find somebody guilty of witchcraft. Judge Danforth responds to Mary's attempt at recanting her earlier testimony by noting the difficulty of determining which testimony to believe:

Danforth, containing himself: I will tell you this - you are either lying now, or you were lying in the court, and in either case you have committed perjury and you will go to jail for it. You cannot lightly say you lied, Mary. Do you know that?

In a trial in which virtually every figure has attempted to extricate him- or herself from the morass of lies and conjecture in an attempt at being spared the hangman's noose, or stoning, Mary Warren's attempt at reclaiming her integrity through an admission of perjury lacks the credibility she so desperately needs to help not only herself but the innocent individuals against whom she has earlier testified. Mary is a weak, pathetic figure who has been content to merely observe the foibles of others, but her weaknesses have dug her into too deep a hole from which to climb out.