False witness and accusation is a standard theme of academic novels. Whether it be plagiarism, sexual harassment, or favoritism and bias. Often, the claims are in fact true, and then the novel has a satisfying sense of the vindication of the truth. But if they are not true, if they have been exaggerated, or the claimant has a history of not being a truthteller, it gets quite messy. And often, the claims prove less than provable.
If the claimant is known otherwise to be unreliable, it still might be the case the the current claim is true. But it is likely that the claimant will be destroyed by cross-examination, especially if there is no further evidence than he-said, she-said. Of course, the accused is unlikely to recover from the false claim, except in terms of a liability suit on the university.
One might think that issues of plagiarism are much easier than sexual harassment and favoritism, but it would seem they may not be if the plagiarism is what I call "brick wall" plagiarism--taking phrases from the source, giving reference, but no quotation marks.
Essentially what happens is that the administrative procedure becomes subject to the legal realm, often by means of a future implied lawsuit by the accused. Settlements leave reputations ruined. Universities have the resources to extend legal proceedings until the accused's resources run out.
Hence, institutions have to investigate the reliability of claimants, even before they share the accusations with the accused. Their future liability may well be much greater than if they did not. This is not nice, and it would seem to make the "victim" subject to accusation. It might discourage reports of harassment or plagiarism or bias. To take accusations seriously, the institution not only must listen to the accuser, but also be sure that what it hears is worth relying on.
Essentially, we are in a litigious world, people have financial and bureaucratic incentives to make accusations, and the institution has an obligation of defending those who are actually victimized. So, the institution needs a devil's advocate who points out weaknesses in accusations. It's not a matter of not believing in such accusations but of making sure those claims will hold up to scrutiny, and so saving the accuser the shame of being found not a truth-teller. You don't want to discover that the accuser is known in the following way by a reliable colleague who has no interest in the allegations but has some experience with the accuser:
Apparently, the person has made some testimony connected to a job action related to some other person. This person is not likely to be a truth-teller. Personally, I would *not* trust this person to be telling the truth, particularly if it involved an accusation against another person. I would absolutely not accept a serious accusation made by this person without credible external verification.
Again, we do not want to discourage the reporting of sexual harassment. At the same time, the process will not possess legitimacy unless effort is made to check the reliability of the claimant--AND keep in mind that unreliable claimants can have genuine claims not to be dismissed out of hand by the reputation for unreliability. If you want the process to have the support of the academic community, the process must encourage reporting of concerns and at the same time be seen as careful in making its allegations. (None of this dismisses concerns about sexual harassment etc. Rather, you need to be seen as protecting the accused against false allegations if you are to have the support of the largee community.)