"The Corps is enjoined from authoring any dredge or fill activities under Nationwide Permit 12 pending completion of the consultation process and compliance with all environmental statutes and regulations", Chief District Judge Brian Morris said in the document on Wednesday.
The plaintiff in the case, the Natural Resources Defence Council (NRDC), in a statement after the decision said the invalidation of the permit blocks the Corps from using a fast-tracked approval process for building any pipelines in the US - including Keystone XL.
The ruling could block construction "through hundreds of water crossings along the Keystone XL pipeline route", the NRDC said.
Keystone is an oil pipeline system that moves Alberta crude oil from the Canadian town of Hardisty to refineries and tank farms in the US states of Illinois, Oklahoma, and Texas. The first three phases of the system are currently operational, however, the construction of the fourth phase, better known as Keystone XL, which is planned to transport oil to Nebraska, has caused a major uproar on both sides of the border.
The proposed section of the pipeline is planned to originate in Hardisty, pass through Baker, Montana where US-produced oil from the Bakken Formation would be added to it, and eventually terminate in Steele City, Nebraska from where it would be redistributed to other refineries and tank farms.