A federal judge has invalidated key land use plans in Montana that were approved under former Bureau of Land Management (BLM) Acting Director William Perry Pendley, a decision that could imperil land use decisions elsewhere and pave the way for a deluge of litigation from environmental groups.

BLM

The ruling issued last Friday was the second substantial decision in the case in the span of a few weeks. U.S. District Judge Brian Morris of the District of Montana ruled in late September that Pendley had served unlawfully for more than a year. Morris blocked him from continuing in the acting position at BLM, which is part of the U.S. Department of Interior.

After the first decision, Montana Gov. Steve Bullock, who filed the lawsuit against Pendley and the Interior, asked Morris to...