The Bush administration, senators, industrialists and farmers repeatedly invoke the term "sound science" to delay or deep-six policies they oppose and dismiss criticism of those they favor.

The administration has waved it at such diverse issues as global warming, beef imports, air pollution and arsenic in drinking water. Last Thursday, Transportation Secretary Norman Mineta used the phrase to slow a congressional bid to raise the U.S. passenger vehicle mileage standard. "An administrative process based on sound science" should precede any change, Mineta said.

No one, however, is sure what "sound science" means.

The phrase has more to do with anti-regulatory lobbying than with laboratory results, said Donald Kennedy, the former head of the Food and Drug Administration and now the editor in chief of the influential magazine Science.

"Sound science is whatever somebody likes," Kennedy said. "It's essentially a politically useful term, but it doesn't have any normative meaning whatsoever. My science is sound science, and the science of my enemies is junk science."

The phrase has been on a roll since 1992, when lobbyists for the tobacco industry argued that no "sound science" showed that secondhand smoke is a health hazard.

Within a year, a group called "The Advancement of Sound Science Coalition" - backed by the Philip Morris company - was invoking "sound science" to oppose not only tobacco curbs but also regulation of hazardous industrial chemicals such as dioxin.

In a 2002 speech to the National Economists Club in Washington, John Graham, who designed the Bush administration's initiative to vet proposed federal regulations, called "sound science" the basis of his agency's reviews.

Graham, then President Bush's administrator of the Office of Information and Regulatory Affairs, said that would result in "a smart process (that) adopts new rules when market and local choices fail, modifies existing rules to make them more effective or less costly, and rescinds outmoded rules whose benefits no longer justify their costs."