The U.S. Court of Federal Claims ruled Friday that thimerosal-containing vaccines do not cause autism, rejecting a second theory advanced by plaintiffs lawyers who blame the injections for contributing to the developmental disorder in children.

The rulings in three test cases mark the second defeat for the plaintiffs lawyers who are litigating autism-related claims in the federal claims court in Washington. More than 5,500 families have filed claims in the Federal Vaccine Compensation Program.