In the abstract, there are three possibilities: she was guilty, she was innocent, or she was raped.
John 8:1-11 tells the story we commonly refer to as ‘the woman taken in adultery’ . The traditional reading, of course, is that the woman was in fact an adulteress. I think that, at the very least, this is an open question. Here’s thoughts on each of the three options:
(1) She was guilty. This has the weight of tradition behind it. The narration in verse 3 does seem to suggest that the woman was taken in adultery. (The narrator could have said, for example, “The woman who the Pharisees claimed was taken in adultery ” but s/he did not.) Proponents of this view might also point to Jesus’ final admonition to “go and sin no more” but that doesn’t persuade me: he says the same thing to the invalid healed on the Sabbath (see John 5:14) where there is no reason to assume that the person in question is guilty of anything besides your average garden-variety sins.
(2) She was raped. The two references to “taken in adultery” (v3 and v4) are both passive verbs which could possibly be interpreted to imply that her involvement in the act was passive, meaning that she was raped.
(3) She was innocent. (Of course, if she was raped, she was also innocent, but here I mean that she was not involved–willingly or otherwise–in any sexual activity; she was just some innocent bystander that the Pharisees nabbed and dragged in front of Jesus.) Note that her only accusers
(1) have their motives impugned by the narrator in v6
(2) are not willing to stand by their accusation
(3) have decided not to follow the law of Moses because they didn’t bring the man to be stoned
(4) have subtly misinterpreted the law of Moses: the word “such” in v5 has a feminine ending so what they are saying, in effect, is that “Moses in the law commanded us, that such a woman should be stoned” which is not what the law says–it says that both parties should be stoned.
So why exactly would we believe their accusation?
Let’s consider Jesus’ response: as I noted above, his admonition to go and sin no more probably in itself isn’t evidence that she is guilty of any great sin. He says he will not condemn (literally: judge against) her. Why would he not render judgment against her if she were guilty? He presumably wouldn’t need witnesses to know if she were guilty.
Interestingly, if you think she was innocent, there are some intriguing similarities between her story and Jesus’ trial:
(1) Both are falsely accused.
(2) Both face a sham trial (compare 7:51).
(3) Both are publicly humiliated and described as being â€œin the midstâ€? (8:3, 9, and 19:18).
(4) Both are victims of religious leaders.
I lean toward option (2) or (3) and away from option (1). But I’ll admit that I can’t make as tight of a case as I’d like. I suspect that may be The Point: the story has been constructed in such a way that the woman’s guilt or innocence is not determinable by the audience. Why should it be? It is none of our business and the story clearly castigates those who thought it was. Regardless of her past, The Point is her present (where Jesus will not allow her to be dehumanized and treated like a life-size object lesson) and her future (where she is invited to live a Christlike life). The Inspired Version adds to the end of verse 11: â€œand the woman glorified God from that hour, and believed on his name.â€?
 In a rare case of unanimity, scholars conclude that 7:53â€“8:11 was not a part of the earliest manuscripts of John. Fernando Segovia summarizes the evidence:
(1) The passage is missing from manuscripts that date before the fifth century.
(2) When the story does appear in the fifth and sixth centuries, it is accompanied by scribal notes that the text is unsure.
(3) In later manuscripts, it appears in several different places (after 7:36, after 7:52, after 21:24, and after Luke 21:38), suggesting that it was a â€˜floatingâ€™ story that was added to different places by different copyists.
(4) The vocabulary has more in common with the Synoptics than with John.
(5) The story breaks the unity between 7:52 and 8:12.
I mention this because it seems negligent to discuss the story without mentioning it, but I am not convinced that the history of the story impacts the discussion above.