President Barack Obama is unilaterally blocking the government from issuing new offshore drilling leases in large parts of the Arctic and Atlantic oceans, which media outlets have described as “permanent.”

But just how “permanent” is Obama’s offshore ban? Not at all.

It’s only “permanent” if President-elect Donald Trump or Congress choose not to challenge it.

On Tuesday, Obama designated “the vast majority of U.S. waters in Daily Caller New Foundationthe Chukchi and Beaufort Seas as indefinitely off limits to offshore oil and gas leasing.” He was joined by and Canadian Prime Minister Justin Trudeau who ordered “all Arctic Canadian waters as indefinitely off limits to future offshore Arctic oil and gas licensing.”

 Obama ordered his drilling ban be “reviewed every five years through a climate and marine science-based life-cycle assessment.” Basically, applying a climate test to offshore drilling on the assumption such reviews will always find it damaging to the environment.

Environmentalists have been urging him for months to use Section 12(a) of the Outer Continental Shelf Lands Act, a 1953 law, to block offshore drilling. Obama’s order is quite unprecedented, and possibly hard to overturn — at least, that’s what activists hope.

Activists argue the law does not give a future president the power to undo a drilling ban. To be fair, there’s no case law on the matter. An effort by Trump to reverse the designation would likely be battled out in the courts for years.

“It’s never been done before,” Patrick Parenteau, an environmental law professor at Vermont Law School, told The New York Times’ Coral Davenport. “There is no case law on this. It’s uncharted waters.”

Past presidents have used the 1953 law to make swaths of ocean off-limits to drilling, and subsequent presidents have scaled back these designations but never done away with them entirely.

“They’ll be arguing about this for years in the courts,” Parenteau said.

Trump, however, will have a Republican-controlled Congress. Lawmakers could amend or even repeal the 1953 law to explicitly allow presidents to undo drilling bans set in place by their predecessors.

The only potential problem would be getting 60 votes in the Senate, but there are some pro-oil Democrats who could cross the aisle to join Republicans.

On the other hand, low oil prices have dampened oil companies’ willingness to drill offshore. Hydraulic fracturing, or fracking, is becoming more efficient , and drilling offshore requires huge capital investments.

Indeed, a Royal Dutch Shell said its 2015 exploratory oil rig “found indications of oil and gas in the Burger J well, but these are not sufficient to warrant further exploration in the Burger prospect.” Oil was too cheap to justify the multi-billion dollar investment.

All that could change if oil prices rise enough.

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This article originally appeared in The Daily Caller

Read the law on administration of the U.S. outer continental shelf at CFACT.org.