I noted here and here the failure of the petitioners' briefs in Obergefell, and the briefs of their amici, to deal with the use of tradition in Heller v. Doe. A search through the 4084 pages of briefs so far shows another interesting near-total omission: only one of the 78 briefs so far (here at 30 n.14) mentions the European Court of Human Rights' 2010 rejection of a similar claim in Schalk & Kopf v. Austria. That court's 1981 decision in Dudgeon v. UK was, of course, very important in Lawrence. The failure to mention Schalk & Kopf, especially in briefs stressing European law, is thus quite striking. Human Rights Watch (here at 5) even quotes Justice O'Connor's statement that "We are going to be more inclined to look at the decisions of (the) European court—and perhaps use them and cite them," but without itself inviting the Court to look at the European precedent most directly on point.
Update (3/17): Seth Tillman writes to clarify that Justice O'Connor was not herself referring to the European Court of Human Rights, but the European Court of Justice, when she referred to "(the) European court." Human Rights Watch's brief at this point cites a law-review article, including the parenthetical, relying on a now-broken web link. I think it is still true that Schalk & Kopf is "the European precedent most directly on point." Because the context of the Human Rights Watch brief was merely the importance of non-US law, Schalk & Kopf's non-citation is thus still quite striking.
Update 2 (3/18): The trickle of amicus briefs continues–three more, but no Schalk & Kopf (or Heller). 81 briefs and 4205 pages, for those keeping score.
Update 3 (3/23): One last Schalk– and Heller-less amicus brief; 82 briefs and 4261 pages total now.
Posted at 1:43 PM