See Chief Judge Kozinski’s concurrence in Bull v. San Francisco — and it’s as a hypothetical, not just because the case happened to involve such a weapon. The weapon was once mentioned as “Carl Gustaf” in an unpublished case, State v. Gustafson, 2003 WL 1566493 (Mont. 2003) (no apparent relation).
UPDATE: Thread winner from commenter Roscoe:
Typical liberal Ninth Circuit opinion. When Judge K reached for the heavy weapons he could have gone with the Javelin or TOW. But no, it had to be something made in Sweden.