The European Court of Justice (ECJ) recently upheld the EU's levying of a carbon emissions tax on non-EU planes flying to EU destinations. The U.S., Canada, and China strongly object, with the U.S. arguing that the International Civil Aviation Organization (ICAO) is the proper body to deal with this.
A couple of thoughts. First, when it comes to concerns over climate change versus concerns over the balance sheets of U.S. airlines, the latter wins out in the Obama admin, it seems. Second, whatever objections are being advanced to the ECJ's ruling, it is probably hard to fault the court's reasoning that sovereignty is not in question here: the planes are flying into EU airspace, after all. But large amounts of money are apparently involved, so this dispute will no doubt continue.