Of course. Many of the circumstances I’ve described are unlikely, although possible. Those unlikely circumstances, though, undermine certain construct - they prove something doesn’t work. E.g. a tribunal can’t successfully make a valid marriage null because, well, it doesn’t have that right, nor aspire to it.
**Of course it’s not a problem with the nature of the process but rather with an individual’s sin. However, the process is affected by that problem, hence that particular proceeding is indeed defective and the verdict is also. **But you don’t dispute this, I think. And no, a person unscrupulous enough to subvert the proceedings won’t probably be scrupulous enough to avoid remarrying. That would take a sick person. An example of someone knowing the verdict is in error would be someone knowing the judges were deceived by a lying witness. I’ve come across only one such case, though.