The European Court of Justice today backed EU plans to levy an emissions tax called the Emissions Trading System (ETS) on airlines.

"The Court of Justice confirms the validity of the directive that includes aviation activities in the emissions trading scheme," it said in a statement

The tax, which means all airlines flying to and from the 27 states of the European Union will face a tax on emissions from 1 January, was heavily opposed by US, Canadian and Chinese carriers.

However, today's judgment held that the tax does not infringe either the principles of customary international law nor the Open Skies Agreement- which allows airlines to fly between any EU country and any point in the US- since airlines can choose whether to fly to EU countries, or not.