I have been pondering the limits of scientific censorship while trying to understand the meaning of the continuing controversy around vaccines and their supposed connection to autism.

It is a story that began when British gastroenterologist Andrew Wakefield and colleagues reported in 1998 that they had found a link between 12 children's vaccinations — for measles, mumps and rubella (MMR) — and the onset of autism.

But then when the findings couldn't be replicated - analyses of large numbers of Finnish children, for example, produced no connection between MMR and autism rates — people such as British journalist Brian Deer began to look again at Dr. Wakefield's research and methodology.

In 2004, Deer pointed out that Wakefield had overlooked mentioning that he had been hired to do the study by a British lawyer preparing a lawsuit against vaccine manufacturers; that many of the kids in the study were also parties in the suit; that Wakefield received upwards of $1 million for contributions to cases against vaccine makers; and that Wakefield was a partner of a company producing what he argued was a safer vaccine. Wakefield sued Deer over the claims, but the suit was subsequently dropped, and all of Deer's legal expenses were paid by Wakefield.

These issues led several of Wakefield's co-authors to disavow the original paper and to an investigation, still ongoing, by the British Medical Council.

But these doubts only arose after class action suits were filed against vaccine makers and government regulators by thousands of parents of autistic children and after celebrities such as Jenny McCarthy made the issue a cause celebre on Oprah and other television shows.

In the meantime, many other scared parents decided not to vaccinate their children and, in so doing, gave rise to the first real measles outbreaks in a decade in the U.S., Great Britain and other European countries. Measles is not something to be taken lightly; it can cause life-altering injuries and even death.

Lawsuits concluded

The lawsuits in both the U.S. and Britain have come to a similar ending as the one against Deer. The British government dropped its support of the one there.

Judge Denise Vowell said that in order to believe the thesis, "an objective observer would have to emulate Lewis Carroll's White Queen and be able to believe six impossible (or at least highly improbable) things before breakfast.

In one of the U.S. cases, the judge, George Hastings, wrote that he had no doubt that, "parents and relatives are sincere in their belief that the MMR vaccine played a role in causing … devastating disorders." He added that, "Unfortunately … they have been misled by physicians who are guilty, in my view, of gross medical misjudgment." He went on to say that, "the overall weight of the evidence is overwhelmingly contrary to the petitioners' causation theories."

In another of the U.S. cases, Judge Denise Vowell said that in order to believe the thesis, "an objective observer would have to emulate Lewis Carroll's White Queen and be able to believe six impossible (or at least highly improbable) things before breakfast."

As the comic books might put it: Pow! Bang! Ooph!

Vested interests

Despite these denunciations, some parents with autistic children still support the vaccine thesis and Wakefield.

In email discussion groups, they attacked Deer, the journalist, and they blamed Big Pharma, the medical establishment and government regulatory agencies for not seeing that — evidence aside — vaccines must be causing autism.

"The combination of vested interest and prejudice seems insurmountable at the moment," wrote one contributor, "but we will prevail."

Why, I wonder, didn't people just give up on the thesis?

On the psychological level, you can see what the parents have to contend with. They have to move from a simple explanation — vaccines cause autism — to effectively no explanation.

Why don't they accept that it was wrong?

On the psychological level, you can see what the parents have to contend with. They have to move from a simple explanation — vaccines cause autism — to effectively no explanation.

For the best the medical community can come up with to replace the vaccine-causes-autism thesis is that the disease is caused by something in the genes interacting with something in the environment. That could even be something in the environment like watching TV while it's raining and snowing. (I am not kidding; this is what a Cornell University study put forward in 2008.)

So now, what you have to believe is that something unfathomable smote your child's genes and turned him or her autistic. Hard to hear; harder to accept.

Hard to believe

But I think it is also hard because we — society at large, the legal system — haven't required some in the medical and celebrity communities to act responsibly. This is particularly important when the consequences are known and hazardous: in this case, the spread of sometimes-fatal childhood diseases.

When faced with this kind of situation in the past, the scientific community has assumed that, in essence, truth would prevail.

I'm not sure that will work in this case. Wakefield has moved to Texas and heads up research at a clinic there. A recent newspaper account says there is a poster on his wall still outlining and promoting his theory. McCarthy continues to argue on television and elsewhere that the vaccine-autism connection is real. On the internet, the desperate parents of autistic children haven't stopped their anti-vaccination campaigns.

I see this and conclude: there are just limitations on free speech.

The most famous example is U.S. Justice Oliver Wendell Holmes's remark that freedom of speech does not include "a man falsely shouting fire in a theatre and causing a panic."

That seems to be exactly where we stand with the vaccine-autism hypothesis.

Originally, there might have been some justifiable belief that the vaccines-lead-to-autism theory was a real fire. Now, all the credible evidence — look for yourself at the U.S. court rulings — suggests it is a false claim and advocating it is causing unnecessary panic.

So on that basis and in the interest of public good, I think legislatures should draft a law or courts should hand down a ruling prohibiting anti-vaccine promoters from claiming that vaccines cause autism.

Might they be right?

But, you might ask, is there no chance whatsoever advocates of the theory are right?

The simplest answer is: nothing in medicine is an absolute absolute. For example, in a new book about the pitfalls of clinical research titled It's Great! Oops, No It Isn't, Ronald Gauch points out that, "the smallest, slightest, infinitesimal possibility that cigarettes [are] not a cause of lung cancer cannot be totally eradicated even today."

We — society at large, the legal system — haven't required some in the medical and celebrity communities to act responsibly.

But does anyone seriously believe that means we should let some doctors tell their patients there is still a doubt cigarette smoking is a cause of lung cancer?

With all the evidence against the claim that vaccination leads to autism in mind, let me repeat my appeal for a legalized type of censorship.

In the interest of public health, and medical truth, and the emotional well-being of autism sufferers everywhere, the legal system should declare that promoting the vaccine-autism hypothesis is the modern equivalent of falsely crying "fire" in a crowded theatre.