Washington ? Vaccines aren’t to blame for autism, a special federal court declared Thursday in a blow to thousands of families hoping to win compensation and to many more who are convinced of a connection.

The special masters who decided the case expressed sympathy for the families, some of whom have made emotional pleas describing their children’s conditions, but the rulings were blunt: There’s little if any evidence to support claims of a vaccine-autism link.

The evidence “is weak, contradictory and unpersuasive,” concluded Special Master Denise Vowell. “Sadly, the petitioners in this litigation have been the victims of bad science conducted to support litigation rather than to advance medical and scientific understanding” of autism.

Science years ago reached the conclusion that there’s no connection, but Thursday’s rulings in a trio of cases still have far-reaching implications — offering reassurance to parents scared about vaccinating their babies because of a small but vocal anti-vaccine movement. Some vaccine-preventable diseases, including measles, are on the rise, and last fall a Minnesota baby who hadn’t been vaccinated against meningitis died of that disease.

The special court represented a chance for vindication for families who blame vaccines for their children’s autism. Known as “the people’s court,” the U.S. Court of Claims is different from many other courts: The families involved didn’t have to prove the inoculations definitely caused the complex neurological disorder, just that they probably did.

More than 5,500 claims have been filed by families seeking compensation through the government’s Vaccine Injury Compensation Program, and Thursday’s rulings dealt with the first three test cases to settle which if any claims had merit. The first cases argued that a combination of the measles-mumps-rubella vaccine plus other shots triggered autism.

“I must decide this case not on sentiment but by analyzing the evidence,” said Special Master George Hastings Jr., writing specifically about Michelle Cedillo of Yuma, Ariz., who is disabled with autism, inflammatory bowel disease and other disorders that her parents blame on a measles vaccine given at 15 months.

Attorneys for the families said they were disappointed and may appeal.

The court still must rule on additional cases that argue a different link — that vaccines that once carried the mercury-containing preservative thimerosal are to blame, if the mercury reached and damaged brain cells. The court has given no timetable for a ruling.