I completely agree about Promissory Estoppel and contract law. I was (perhaps unclearly) trying to demonstrate that other areas of the law do address the principle of relying on a promise when making a decision.

I think the principle could and should apply to some extent in this situation here too.

Something like: if you were misled into making a confession - perhaps relying on a promise or lie told to you by the interviewer - then at the very least that confession should be considered deeply suspect.