On April 13, the petitioning candidates who want to be on the ballot for the Montana special U.S. House election filed a brief in the Ninth Circuit. The brief documents that one of the candidates, Thomas Breck of the Green Party, did collect over 400 valid signatures (the counties checked them) on Sunday, April 9, the very day after the U.S. District Court said 400 signatures would be enough.
The Ninth Circuit brief points out how unfair it is for the U.S. District Court to have set the requirement at 400, after it was too late to get the 400 signatures. The case is Breck v Stapleton, 17-35310. A decision could come down at any time. There will be no oral argument in the Ninth Circuit.