To be fair that wasn't the user I asked for sources, we should see if they have something still. Also that wiki link was fairly interesting, particularly the Hart case in 2014 in which the Canadian Supreme Court found that using the confession drawn from the Mr. Big technique was inadmissible (although their was a later exception in a relation to a violent case that already had supporting evidence). To me, this would actually support the point the others were making a bit at least... If we can believe that this would have been more common prior to 2014, at least in Canada then MAYBE that could indicate that it was/is commonplace in the US which AFAIK does not have a ruling like in the Hart case.