President Barack Obama permanently banned future oil and gas drilling in large swathes of the U.S.-owned Arctic and Atlantic Ocean on Dec. 20.
The ban affects large parts of the Beaufort and Chukchi seas in the Arctic and a stretch of Atlantic canyons that span from Massachusetts to Virginia, The Washington Post reports. Combined with an already existing five-year drilling moratorium in the Atlantic, the act is set to block oil exploration in much of the eastern seaboard.
The move is the latest act by Obama to shore up his environmental legacy a month before he exits the White House. President-elect Donald Trump has pledged to pursue a pro-oil policy of tapping into the country's as-yet untouched energy reserves.
Obama's act was issued in conjunction with the Government of Canada, which also issued a ban on new oil and gas leasing in its Arctic waters, subject to review by future administrations, CBS News reports.
Neither ban affects existing oil and gas drilling leases and oil-extraction activities in state waters.
The U.S. President based the ban on a provision of a 1953 law to permanently ban offshore leases in the relevant waters of the Arctic and Atlantic Oceans. The statute reads: "The president of the United States may, from time to time, withdraw from disposition any of the unleased lands of the outer Continental Shelf."
Environmental groups hope the measure, despite having been enacted by the executive, cannot be reversed by future presidents.
The White House expressed confidence Obama's order will resist any future legal challenge and pointed out the statute's language does not grant authority to future presidents to undo the permanent restriction.
The President recognized the importance of the Chukchi and Beaufort seas to native Alaskans seeking subsistence and the vulnerability of the oceanic ecosystem to oil spills in framing his directive.
"This decision will help protect existing lucrative coastal tourism and fishing businesses from offshore drilling, which promises smaller, short-lived returns and threatens coastal livelihoods," said Jacqueline Savitz, the advocacy group Oceana's senior vice president.
It is certain pro-oil industry groups will fight to overturn the measure.
The American Petroleum Institute cited President George W. Bush's simple 2008 memorandum to lift a drilling ban on all Outer Continental Shelf lands save for marine sanctuaries.
“Fortunately, there is no such thing as a permanent ban,” said the institute’s Erik Milito.
Environmentalists signaled they stand by ready to defend Obama's latest measure.
"If Donald Trump tries to reverse President Obama’s withdrawals, he will find himself in court," said Marissa Knodel of Friends of the Earth.