The Department of Transportation’s decision on Friday granting Norwegian Air International the right to fly internationally into and out of the United States remains a hotly contested issue.

Proponents of the deal say it will further open international travel through competition and help drop fares.

"There is zero downside to allowing more low-cost carriers into U.S. airports: it's a policy that's good for consumers, stupendous for U.S. economic and job growth, and even good for U.S. airlines because it broadens the market for domestic connector flights," Roger Dow, president-CEO of the U.S. Travel Association, said in a tatement. "More choices for American travelers and more capacity to bring foreign visitors and their dollars to U.S. shores is the unimpeachably correct decision, period."

Critics have derided the decision after noting – for more than 18 months – that Norwegian’s plan to enter the global marketplace in the U.S. includes having a home base in Ireland, where it can skirt strict labor laws in Norway and hire below-market flight crews from other countries.

READ MORE: Critics Still Complaining About Norwegian

Norwegian Air has denied the claims and said it is in full compliance with the Open Skies Agreements, which U.S.-based carriers American, Delta and United have disputed.

Edward Wytkind, president of the Transportation Trades Department, AFL-CIO said the DOT’s decision betrays American aviation workers.

“Unless reversed, this decision threatens a generation of U.S. airline jobs and tells foreign airlines that scour the globe for cheap labor and lax employment laws that America is open for business,” he said in a statement, calling on President Obama to reverse the decision. “Clearly, a Norwegian-owned airline that is based in Ireland for the purpose of evading Norway’s labor and tax laws, and that will hire crews under Asian contracts, is in violation of these explicit labor protections, and should be denied entry into our marketplace. With this decision, the Obama Administration has failed to enforce the very labor protection it negotiated and sold as a breakthrough in aviation trade policy.”

Even Congressional leaders are involved.

“DOT’s decision has guaranteed a race to the bottom in our transatlantic aviation market,” Rep. Peter DeFazio (D-Ore.) said. “Norwegian is a virtual airline, set up under a flag of convenience to exploit weak labor laws in other countries like Singapore, save money, and undercut competition.”

But in a nine-page decision, Jenny Rosenberg, acting assistant secretary for international affairs, wrote: “This case is among the most novel and complex ever undertaken by the department. “Regardless of our appreciation of the public policy arguments raised by opponents, we have been advised that the law and our bilateral obligations leave us no avenue to reject this application.”