I might be wrong, but I think they did prove a link - had something to do with predisposition and mitochondrial DNA.
This is a long-running bone of contention in the vac - anti-vac debate.

As yet, no studies have managed to find a link between autism and the MMR vaccine. And there have been some pretty large-scale studies done into the matter. However, there are a lot of factors at play in determining this kind of link. For one, how do you really determine whether the MMR was linked to the onset of autism? How do you define it? If you got your autism the day after, do you consider that linked? What about a week after, or a month after? Depending on how you define these things, the results of research can change considerably.

There remains no doubt that there is a large body of anecdotal evidence - from parents - that they had very normal children until they gave the MMR vaccine and then, suddenly, their child developed autism. As our paediatrician (whom we trust implicitly) said to us when we discussed it - "where there's smoke, there's fire". To give an example - a generation ago, a fringe group of doctors and surgeons were beginning to speak out against tobacco smoking and suggest a link with lung cancer. For a decade, they were dismissed, and large, 'reputable' studies - funded in large by tobacco companies - failed to prove a link.

Now, of course, many years on, we know without a doubt that the link between tobacco smoking and lung cancer does exist.

The link with between the MMR vaccine, autism, and mitochondrial DNA was suggested by an anti-vaccination campaigner and researcher as an alternative theory to the theory that autism was caused by the mercury or thiomersal used in the MMR vaccine, as that additive was withdrawn from use in 2000, but there are still reports of autism relating to the vaccine.

The court case in the US was that of a mother who sued her state for mandating the MMR vaccine and the resultant development of that the court termed an "autism-like brain disorder". The court initally found in favour of the mother, but that decision was later overturned. It should be stressed that a court case such as this is not trying to determine the medical validity of the claim, but the legal validity of it. In this case, the court case didn't really prove there was a link, it proved that there was enough likelihood of a link that the state was negligent in mandating the use of the vaccine. But as I said, it was later overturned on appeal.

There is no hard-and-fast evidence on the MMR vaccine. It should be - needs to be - every parent's decision, and the unfortunate thing is that parents are forced to make that decision without all of the facts because of the government's blinkered one-size-fits-all vaccination campaign.