Jan 21 (Reuters) - President Donald Trump in an

executive order on Monday revoked a ban imposed by former

Democratic President Joe Biden on new offshore oil and gas

development along most of the country's coastlines. Trump is

certain to face legal challenges over his authority to do so.

WHAT DID BIDEN AND TRUMP DO?

Biden on Jan. 6 used his authority under the 70-year-old

Outer Continental Shelf Lands Act to withdraw all federal waters

off the East and West coasts, the eastern Gulf of Mexico and

portions of the northern Bering Sea in Alaska from oil and gas

drilling.

Biden said the move aligned with his efforts to combat

climate change, saying "drilling off these coasts could cause

irreversible damage to places we hold dear and is unnecessary to

meet our nation's energy needs."

Trump had long pledged to expand oil and gas development. He

revoked the offshore drilling ban on Monday, one of dozens of

actions taken by Biden that Trump repealed on his first day in

office.

Trump also revoked an earlier action Biden took in March

2023 that prevented oil and gas drilling in 2.8 million acres in

the Arctic Ocean.

CAN TRUMP DO THAT?

Legal experts say the question of whether a president can

revoke a predecessor's decision to invoke the Outer Continental

Shelf Lands Act (OCSLA) and withdraw areas from mineral leasing

and drilling remains legally unsettled.

While the law expressly grant presidents the authority to

set aside lands, the 1953 measure is silent on whether they are

able to revoke prior decisions. The question has only ever been

addressed once in court, during Trump's first administration.

WHAT WAS THAT CASE?

Environmental groups sued after Trump, in April 2017, issued

an executive order designed to revoke a similar decision by

Democratic former President Barack Obama. Obama invoked OCSLA

and put the Arctic's Chukchi Sea, part of the Arctic's Beaufort

Sea off-limits to oil leasing, along with a large swath of

Atlantic Ocean off the U.S. East Coast.

In 2019, U.S. District Judge Sharon Gleason in Anchorage

ruled Trump's order was unlawful. "Had Congress intended to

grant the President revocation authority, it could have done so

explicitly, as it had previously done in several (but not all)

of its previously enacted upland laws," she wrote.

Trump's administration in defending his order had cited

language in the OCSLA stating that a president may "from time to

time" withdraw unleased lands, saying this carried with it an

authority to revise prior withdrawal decisions.

But Gleason, an Obama appointee, in her ruling said the

OSCLA left only Congress with the power to overturn withdrawals

of land.

Before the San Francisco-based 9th U.S. Circuit Court of

Appeals could rule on the Trump's administration's appeal of her

decision, Biden took office and on his first day revoked Trump's

order, mooting the case.

WILL TRUMP'S NEW ORDER END UP IN COURT AS WELL?

Trump's executive order to undo Biden's action will likely

invite a new legal challenge from environmentalists and

potentially settle the question of a president's revocation

authority.

But Biden's order itself is already being challenged in

court in two separate lawsuits, including one by five Republican

state attorney general and two industry trade groups American

Petroleum Institute and the Gulf Energy Alliance and another by

Republican Texas Attorney General Ken Paxton, alongside oil and

natural gas producer W&T Offshore ( WTI ).