Supporters of genetically modified foods frequently claim that their position is based on "sound science," in contrast to the "junk science" practiced by anti-GM activists. Their definition of "sound science" is rooted in a set of norms for appropriate scientific behavior. A true scientist, the GM defenders say, would only argue his case with great care on the basis of sound, peer-reviewed data open to critical scrutiny. In reality, however, these standards of scientific probity are only demanded from perceived critics, while anything goes with scientists who support GM foods.