The European Court of Justice’s (ECJ) ruling on a case brought by U.S. carriers against the EU’s emissions trading system (ETS) is expected to mirror the judge advocate’s decision earlier this year, and environmental groups already are claiming victory.

The judge advocate sided with the EU in the matter by arguing that inclusion of international aviation in the ETS is in accordance with international law, a claim the U.S. and a growing number of countries dispute. The U.S. has stepped up its rhetoric, with Secretary of State Hillary Rodham Clinton and Transportation Secretary Ray LaHood threatening “appropriate” action should the EU press ahead with extending ETS to all carriers flying into and out of European airports.

The U.S. Transportation Department (DOT) has ordered U.S. and European carriers to submit to DOT all data collected for the ETS. Clinton’s and LaHood’s letter, along with President Barack Obama’s comments last month in Brussels, telegraphs that opposition to the ETS has moved to the highest levels of the U.S. government.

Clinton’s letter also signaled that the U.S. is exploring its options. One of these options, according to Nancy Young, Airlines for America (A4A) VP-environmental affairs, is for the U.S. to impose retaliatory measures against the EU and to use funds raised this way to reimburse airlines for the costs of the ETS. Some in the industry believe that this could be the reason behind the DOT’s recent directive mandating that ETS data be turned over. “I take the U.S. government at its word that they’re looking at all the options,” says Young. “They’ve upped the political dialogue.”

But during the recent Joint Committee meeting between the EU and the U.S. on the implementation of the open-skies agreement, U.S. officials pushed the EU to back away from the ETS, says Pamela Campos, an attorney for the Environmental Defense Fund. To change European law, however, could be a two-year process, so it is unlikely that the EU will back down from the ETS, she says. Counters A4A’s Young, “If there is the political will to change the law, the EU would do so.”

“We need something that will address this issue at the global level,” says Campos, who notes that when the EU directive was issued in 2008, the expectation was that equivalent carbon-mitigation measures in other countries would have been developed and those countries would have waived out of the ETS. The International Civil Aviation Organization (ICAO) recently voted to censure the EU for the ETS. “Airlines have tried at every turn to block this,” says Bill Hemmings, program manager for Transport & Environment, a Brussels-based environmental activist group. “A cabal of countries, with the [U.S.] State Department behind the scenes, managed to get ICAO to rule against the ETS.”

This is not strictly true, says Young. ICAO has had a framework approach to mitigating emissions, one that includes more alternative fuels, better air traffic control procedures and more investment in technology and operations. The EU’s insistence on the ETS has held up this process, says Young.