[mdholloway]

This is true, but only to a point. In principle, if the reasoning is flawed in some obvious way (say, writing a memo on executive power during wartime without citing Youngstown Steel, the leading case on the subject), other people with requisite training will sooner or later recognize that, and the error will be corrected.

Of course, this requires public scrutiny to work. Hence the problems with secret legal memos and secret court opinions.