The government misrelies upon United States v. Cadet, 727 F.2d 1453 (9th Cir. 1984), and United States v. Gatto, 763 F.2d 1040 (9th Cir. 1985), to argue that ....
A quick NEXIS search through the NEWS;CURNWS and NEWS;ARCNWS files for "misrely," "misrelies," or "misrelied" found zero mainstream publications using the term. (It did come up with one law review article.) Neither the OED nor the dictionaries available through onelook.com gave any definitions for "misrely." Google search likewise yielded very few examples; "misrely" produced only 158 items (not the number Google indicated at first, but the number one sees when one gets to the end of the Google results) — nearly all were either misspellings of "miserly," word lists, or junk. Likewise for "misrelied" (95 items) and "misrelies" (89 items).
But a Westlaw caselaw search found 30 cases, one from 1939 and the rest from 1973 or more recently, using the term or its variants. A search through law review articles found 9 items, though one was a quote of a case. That's not a lot of hits, but it suggests that the word is in some regular use: By way of comparison, eminently normal (again, not very common, but normal) words such as "enigmatically" (147 uses in caselaw), "pessimistically" (32 uses in caselaw), or "defeatist" (100 uses) are within an order of magnitude of this frequency (though I acknowledge that for "misrely" I looked at three grammatical forms of the term and not just one).
So this strikes me as an unusual example — a term that in Nexis-available sources is used exclusively by lawyers, that appears in its various forms on nearly 40 occasions in published legal work, and yet doesn't seem inherently tied to legal concepts. Why would the word have emerged among lawyers but not among others?