Veterans and their families asked a federal appeals court Wednesday to reinstate dozens of lawsuits alleging that a government contractor caused health problems by using burn pits during the wars in Iraq and Afghanistan.

More than 60 lawsuits allege that KBR Inc. — a former Halliburton subsidiary — dumped tires, batteries, medical waste and other materials into open burn pits, creating harmful smoke that caused gastrointestinal illnesses, neurological problems, respiratory problems, cancers and other health issues in more than 800 service members.

The lawsuits, which were filed in multiple districts around the country and then consolidated, also alleged that at least 12 service members died from illnesses caused by the burn pits.

Last year, a judge in Maryland dismissed the lawsuits, finding that the U.S. military made all of the key decisions and had control over KBR's use and operation of burn pits. The lower court found that analyzing military decision-making during war is a political question not appropriate for judicial review.