The military contractor DynCorp International has mostly defeated claims that its use of an aerial herbicide harmed Ecuadorean citizens two decades ago. But the long-running litigation isn’t quite over, thanks to an appeals court ruling issued on Friday.

In an 11-page decision, the U.S. Court of Appeals for the D.C. Circuit held that a trial judge properly tossed most of the plaintiffs’ claims. The D.C. Circuit revived some tort claims brought by a group of Ecuadorean plaintiffs, however, finding that the judge erred in ruling that they required expert testimony to make their case.