Food cops who think your weight is their business are bent on slimming Americans down by any means necessary. That includes happily ignoring such commonplaces as evidence, logic, and common sense. Reaching deep into their toolbox to hammer companies that advertise food to children, they’re now invoking the “precautionary principle” — a bizarre theory that insists everything should be banned until it’s proved absolutely safe.

Susan Linn, two-time speaker at the obesity-lawsuit-pushing Public Health Advocacy Institute (PHAI) and dedicated opponent of all forms of advertising, recently told Obesity Policy Report: “I think that we need to take a leaf from the environmental movement and think about the precautionary principle.” As Wellesley professor Robert Paarlberg has noted in The Wall Street Journal, the precautionary principle insists that:

…powerful new technologies should be kept under wraps until tested for unexpected or unknown risks as well. Never mind that testing for something unknown is logically impossible (the only way to avoid a completely unknown risk is never to do anything for the first time).

It’s not terribly surprising that activists who want to ban all advertising to children would rely on the precautionary principle. After all, there’s no evidence that food advertising causes childhood obesity. In February, the Kaiser Family Foundation released an exhaustive analysis of the subject that purportedly found a link between food advertising and childhood obesity. The only problem: Not one out of forty studies examined by the Foundation could actually make this conclusion. In fact, Kaiser admitted that television watching might not cause obesity at all, saying: “Being obese may cause children to engage in more sedentary (and isolated) activities, including watching more television.” Even Kelly “Big Brother” Brownell admits “there is only circumstantial evidence that the ads cause poor eating.”

Of course, evidence has never been Linn’s strong suit. She complained at PHAI’s 2003 conference: “Rampant commercialism, in and of itself, is unhealthful, and the food industry contributed to that.” Linn has dedicated herself to complaining about marketing to young children — though that doesn’t stop the “ventriloquist/psychologist” from using puppets to get across her anti-corporate ideology. She’s also worked with Ralph Nader’s Commercial Alert for at least five years.

Linn would do well to listen to former Federal Trade Commission chairman Timothy Muris, who points out: “Today’s kids actually watch less television than previous generations and have many more commercial-free choices.” And while Linn complains that ads “contribute to family stress and the food children ask for,” Muris states what every parent knows: “There’s lots of things government can do, but I don’t think government can prevent children from nagging their parents.”

Recognizing that physical activity levels are far more important than advertising, Muris noted: “Our dogs and cats are fat and it’s not because they’re watching too much advertising.” He went on to insist:

A ban on advertising is impractical, ineffective, and illegal … It’s impractical because, although kids see many food ads on children’s programming, most ads they see air on programs that are not directed to them. The FTC’s 1978 proposal to ban advertising on programs for which young children comprised at least 30% of the audience would have affected only one program — the now iconic “Captain Kangaroo.”