U.S. Justice Department attorneys want an appeals court to let construction proceed on the Keystone XL oil pipeline from Canada. But opponents say President Donald Trump is trying to skirt the law by issuing a new permit for the project.

The Trump administration has asked the 9th U.S. Circuit Court of Appeals to reverse a lower court ruling that blocked construction of the $8 billion pipeline.

Government attorneys say the November ruling that more environmental study was needed is now meaningless. That's because Trump issued a new permit to developer TransCanada in March.

FILE - In this Nov. 3, 2015 file photo, the Keystone Steele City pumping station, into which the planned Keystone XL pipeline is to connect to, is seen in Steele City, Neb. President Donald Trump has issued a new presidential permit allowing construction of the Keystone XL oil pipeline, two years after he first approved the long-stalled project. Trump said the permit issued Friday, March 29, 2019, replaces one granted in March 2017. (AP PhotoNati Harnik)

FILE - In this Nov. 3, 2015 file photo, the Keystone Steele City pumping station, into which the planned Keystone XL pipeline is to connect to, is seen in Steele City, Neb. President Donald Trump has issued a new presidential permit allowing construction of the Keystone XL oil pipeline, two years after he first approved the long-stalled project. Trump said the permit issued Friday, March 29, 2019, replaces one granted in March 2017. (AP PhotoNati Harnik)

In a legal filing late Wednesday, environmental groups asked the appeals court to keep construction blocked.

Legal experts say the case is another test of Trump's use of presidential power to get his way.

President Donald Trump speaks during a news conference at his Mar-a-Lago estate in Palm Beach, Fla., Friday, March 29, 2019. (AP PhotoManuel Balce Ceneta)

President Donald Trump speaks during a news conference at his Mar-a-Lago estate in Palm Beach, Fla., Friday, March 29, 2019. (AP PhotoManuel Balce Ceneta)