How to assess the damage that the conspiring witnesses would have caused if they hadn't been determined to be conspiring: especially with monetary cases, such as the value of a ketubah, for example. But if he were to have died, he'd only have lost the value of the ketubah, without having to pay it out. So the risk of her having been widowed becomes part of the equation - including whether someone might have been willing to buy out the ketubah. Likewise, a case where the person they're testifying against has done the thing they're testifying about - and in that case, how much damage have they caused him? Also, a caveat about whether a loan is made with a promissory note - and how the default 30 days before asking for your money back kicks in only with a formal IOU. Plus, a concern about opening a collar on a shirt - and how that would be a violation of Shabbat, in contrast to removing the stopper from a wine barrel.