Mann filed a lot of lawsuits over this and has lost all of them:
https://www.steynonline.com/11508/youre-once-twice-three-tim...
He didn't spend 9 years fighting a very expensive lawsuit and then, when he finally had a chance to prove that his work wasn't fraudulent in front of a judge, decide he was busy with other things lol! He refused to present the relevant evidence because his goal from the start was an ideologically motivated litigation war, in his own words:
thanks Phil. there is a possibility that I can ruin National Review over this. Going to talk w/ some big time libel lawyers to see if there is the potential for a major lawsuit here that will bring this filthy organization down for good.
But then National Review was removed from the case and so there was no chance for him to achieve his goal via abusive litigation anymore.
Mann is unquestionably a fraud even in the eyes of his colleagues. He deliberately deleted data that disproved his reconstruction because he knew that if he was honest "skeptics would have a field day":
As lead author, Mann decided to omit the Briffa data without the input of his other lead authors.. . . Mann’s own collaborators cautioned him against the deletion. IPCC TAR Coordinating Lead Author Chris Folland wrote to Mann that Briffa’s data “contradicts the multiproxy curve and dilutes the message rather significantly.”. . . Briffa himself urged Mann not to succumb to “pressure to present a nice tidy story” by “ignor[ing]” his post-1960 results. . . . Mann agreed with them on the merits but bemoaned the data’s political impact: “[I]f we show Keith’s series . . . skeptics [will] have a field day.”