Does anyone know if there is any equivalent or usage of the principle "פה שאסר הוא פה שהתיר" or a "מגו" in American law that could help illustrate the principle?

A basic explanation of the principle of פה שאסר is that when a person makes a claim that includes a previously unknown piece of information, the person can qualify the statement. For example, if a person were to say to his friend "this land belonged to your father, but I bought it from him" the person would be believed. Although he has no evidence that the land belongs to him now, since the son did not know that his father even had this piece of land, the person is believed because had he kept quiet the son wouldn't have even known about the land in the first place.

Another example would be if a woman, who is not known to have been ever married, says that she was married (Therefore Prohibited to other men) but is now divorced (and therefore permitted to marry another). She is allowed to marry another man without proof of divorce. The reason is the very statement that would have prohibited her also includes a statement that permits her.

In other words my understanding is that we view the two statements as a unit. If we are going to believe the first part of the statement then we should believe the second half. If we don't accept the second half, then on what basis are we accepting the first half.

This is a brief treatment of the subject. I hope it gives some clarification of what I am looking for.

Are there any examples in American Law?

For example of Halachik usage see כתובות דף טז

  • Hmm. I see your perspective, but I am trying to get American Law examples that may help illustrate the principle. Furthermore, one may argue the rule you quoted is dealing with comparative religion. I am asking a law question not a religion question. Furthermore one could argue that Sheva Mitzvos Bnei Noach demand a court system. We might debate that point. Additionally see here for a usage already accepted: judaism.stackexchange.com/questions/18353/… Thanks for re-considering this. – RCW Jun 26 '15 at 4:06
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    I suggest migrating to Law.SE – Noach MiFrankfurt Jun 26 '15 at 4:15
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    I guess the edited version is on-topic now, and I'll reopen, but −1 because you seek an example of a rule without even explaining what the rule is. – msh210 Jun 26 '15 at 5:45
  • I'm pretty sure neither concept exists. If it does in some form, it would be unlikely to be very illustrative because it would still be quite different. – Yishai Jun 26 '15 at 15:52
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    I'm voting to close this question as off-topic because it is not about Judaism, although it may provide a metaphor useful to Judaism. – mevaqesh Apr 5 '17 at 7:11