Even when a judge does not cite to nonlegal academic journals or newspapers or anything else, she is still, although less obviously, relying on sources of information that are importantly factual, that may very well be contested, and that wind up being part of the law in a somewhat under-the-table manner, even apart from the way in which such propositions may produce adverse consequences for one of the parties without that party having much or any opportunity to challenge those propositions by the normal adversarial processes, including but not limited to cross-examination.

Unknown, Frederick Schauer - Thinkin…, loc. 397