"The Trump administration tried to force this dirty pipeline project on the American people, but they can't ignore the threats it would pose to our clean water, our climate, and our communities", Mr Hayes added.
The ruling is a major victory for environmentalist groups that sued to stop the project and for the Native American tribes that have protested against it for years.
If built, it would transport around 830,000 barrels of crude oil per day from Alberta, Canada, and the Bakken Shale Formation in Montana to facilities near Steele City, Neb.
Mr Obama rejected the scheme in 2015 following a recommendation from the Environmental Protection Agency, citing concerns over it increasing USA dependence on fossil fuel.
Trump granted a permit that allowed energy firm TransCanada to build the controversial Keystone XL pipeline shortly after taking office.
No immediate impact in oil markets is seen, as the pipeline isn't scheduled to come online for years regardless of the ruling.
What did the ruling say?
"The department's 2017 conclusory analysis that climate-related impacts from Keystone subsequently would prove inconsequential and its corresponding reliance on this conclusion as a centerpiece of its policy change required the department to provide a 'reasoned explanation, '" Judge Morris said.
"An agency cannot simply disregard contrary or inconvenient factual determinations that it made in the past, any more than it can ignore inconvenient facts when it writes on a blank slate", Morris wrote.
United States proposes banning asylum through southern border
The new rule comes as a so-called caravan of migrants from Central America travels north by foot through Mexico to the US border. US Army troops enter a compound where the military is erecting an encampment near the US-Mexico border crossing at Donna, Texas.
Titans defeat Cowboys Monday night
Prescott is under contract through 2019, but the Cowboys can begin negotiations on an extension after this season if they choose. The coaching staff has to understand the strengths of each player on the team and learn how to play off of it.
Arsenal held at home by Sporting
And while Nelson may not be a ready-made replacement for Welbeck , Emery says he is keeping a keen eye on his progress. But I think the players were concentrated on the match and we forgot this injury the next minute on the pitch.
Eddie Jones names his favourite All Blacks
New Zealand go into the game on the back of a 69-31 win over Japan in Tokyo last Saturday with a side featuring eight debutants. But there's a lot of good coaches out there. "You've got to play a certain way against them, there's no doubt about that.
Pres. Trump says government will halt if Dems investigate him
The president also mocked Republicans who did not "embrace" him on the campaign trail , and went on to lose their election races. Republicans devoted their resources to close races, not to trying to prevent Democrats from running up the score in urban areas.