When I was reporting the story on vaccines and autism for the current issue of the magazine, everyone warned me that despite a sweeping decision by the “vaccine court” that neither thimerosal nor the MMR vaccine cause autism, the belief that either or both do was not going to fade away. Hard on the heels of that February 12 decision by the court, another case—decided in July 2007 but being released only now—went in favor of parents who believe the MMR vaccine caused their son’s Pervasive Developmental Delay (of which autism is one form).

In the case, the parents of Bailey Banks, now 10, argued that their son had a seizure 16 days after his first MMR, in 2000. That, they said, led to Acute Disseminated Encephalomyelitis (ADEM), a rare neurological disease, which in turn led to PDD.

The first question for the court, then, was whether Bailey had Acute Disseminated Encephalomyelitis, and its answer was yes, based on medical records. It then addressed the question of whether the MMR vaccine can cause ADEM, and here there was precedent: Two previous vaccine cases, in 1994 and 2001, had led to decisions that ADEM can be caused by natural measles, mumps, and rubella infections, as well as by measles, mumps, and rubella vaccines. In Bailey’s case, the court ruled, the MMR had indeed caused his Acute Disseminated Encephalomyelitis.

For the final step, the court wrestled with whether Acute Disseminated Encephalomyelitis can cause pervasive developmental delay, and whether it caused Bailey’s. (Just to reiterate, the issue was PDD, not autism. As the court said in its decision, Bailey “more likely than not suffers from PDD, and not from autism.”) Here, the medical literature leaves plaintiffs much more room than does the literature on classical autism. The government argued against the claim that ADEM can cause pervasive developmental delay, of course, acknowledging “that Bailey currently suffers from PDD, and that the MMR vaccine can cause ADEM" but disputing "the biologic plausibility [of] whether ADEM can lead to PDD.”

Here, the science is not so negative as it is in the case of vaccines and classical autism. As the court said in its decision, “Bailey’s ADEM was severe enough to cause lasting, residual damage, and retarded his developmental progress, which fits under the generalized heading of Pervasive Developmental Delay, or PDD. Additionally, this chain of causation was not too remote, but was rather a proximate sequence of cause and effect leading inexorably from vaccination to Pervasive Developmental Delay.”

The decision is being announced so long after the fact because, under the rules of the vaccine court, after a special master decides that a plaintiff is entitled to compensation the parties (Bailey’s parents and the U.S. government, the defendant) must negotiate a settlement, Michael McLaren, the Banks’s lawyer, told me Tuesday evening. That required determining what Bailey would need for his care for the rest of his life—less now, when he is living with his parents and attending a school for autistic children, but more later, when he is on his own. The government agreed to a lump sum of $750,000, and an annuity that will provide as much as $70,000 to $100,000 a year for Bailey once his parents are not able to care for him.