A reader asked me which deck I finally decided on.
Unfortunately, I couldn’t find any that had a legal motif or a crime motif; but I did come across an Oz deck — the land, not the HBO show — that looked cute and that reminded me of reading the books when I was a child. (I read the books in Russian, so much of what I read may have been the purely Russian sequels; I can’t remember for certain.) So that’s what I decided to use: I passed around a normal card deck and the Oz deck, and students picked any card to sign; now, to choose a student to call on, I just pick a card at random.
Thanks to all who offered suggestions for possible decks — and if any of you can find a good source for Mexican Loteria cards (whether online or in some store in L.A.), please let me know, since those also struck me as potentially fun for future classes.