Montana requires petitions to qualify a new party to submit 5,000 signatures. In addition, the petition must include a certain number of signatures from at least one-third of the 100 state house districts. The house districts are all of approximate equal population, but the law requires a range of between 55 and 150 signatures from each of the house districts for which signatures are submitted.
On March 20, U.S. District Court Judge Brian Morris, an Obama appointee, upheld this law, in a case filed in 2018, Montana Green Party v Stapleton, 6:18cv-87. The judge cited two cases upholding distribution requirements, but those cases, from Colorado and Missouri, do not deal with unequal distribution requirements. They both include equal population units, and the number of signatures needed in each unit is the same (either an identical number of signatures, or percentage of some base such as the number of votes cast or the number of registered voters).
The U.S. Supreme Court in 1969 settled that when distribution requirements are unequal, they are unconstitutional. Since then unequal distribution requirements have been struck down in 15 other cases, most recently in Pennsylvania. The Montana Green Party decision will be appealed to the 9th circuit. Here is the 15-page opinion. The case had originally been in front of a magistrate judge, and he also had made the same legal errors. The magistrate judge didn’t even mention the U.S. Supreme Court decision from 1969 on this issue. The U.S. District Court judge did mention it, but he didn’t discuss its holding.