On August 21, 2018, the Montana Supreme Court removed the Green Party from the 2018 ballot. However, the court at that time did not explain why it did that.
On January 30, 2019, the Court explained why it acted as it did. Use this link to read the opinion. Choose “Active Dockets”. When that opens, enter this case number: DA 18-0414. After you click on the link, then click in the right-hand column on “opinion”, near the top. Thanks to Jim Riley for advice on the link.
Meanwhile, the Green Party is in federal court, arguing that the ballot access law is unconstitutional, on the basis that the deadline is too early and the distribution requirement is unequal.