Continental Airlines is not liable for not warning passengers about the risk of blood clots during an international flight, a U.S. federal appeals court ruled on Wednesday.

Guy Caman sued Continental after he was diagnosed with deep vein thrombosis (DVT) following a flight from Los Angeles to Paris in 2002. A lower court ruled in favor of Continental, and on Wednesday the U.S. Ninth Circuit Court of Appeals upheld the ruling.

Caman argued he suffered an accident as established under the Warsaw Convention governing air travel.

“We hold that Caman cannot establish his DVT was the result of an ‘accident’ because he cannot show that it resulted from an ‘unexpected or unusual event,’” Morrison England wrote for the three-judge panel.

Growing awareness of the problem of DVT has prompted a number of lawsuits. Last December, Britain’s high court also held that DVT, which can sometimes prove fatal, is not an accident under international rules and thus airlines are not liable.

Airlines maintain that the Warsaw Convention protects them from having to pay compensation to passengers for medical issues during normal operation of an aircraft.