In principle, the carbon tax can be contested via the WTO international arbitration procedure. A number of EU's energy-intensive companies are currently receiving free CO₂ emission credits within the EUETS system. Amongst others, such favors are enjoyed by steel and cement producers. In addition, EU member countries are allowed to return a portion of revenues generated through ETS to energy-intensive enterprises.

Exporting countries may view the new tax as a direct protectionism and discrimination or demand their fair share in free greenhouse gas emission credits within the protected industries.

It is noteworthy that the European Commission is prepared to be proactive and plans to revoke the free credits issued to polluting industries under the EU ETS.

Affected companies may also insist that the new tax does not meet the WTO principles. Indeed, the WTO principles do not really provide for comparison and discrimination against any goods on the basis of their carbon intensity. Although, in this case it will be more difficult to prove the existence of protectionism, and such trade dispute may take years. Besides, it has to be taken into account that green agenda is currently not only dominating international politics and economy, but reinforces its positions.