A news story about tobacco legislation opening the door to obesity lawsuits quoted a law school professor: "The legal theories are not inapplicable in the broadest sense of the word to fast food." My question is, is there a reason for using the double negative construction rather than saying the theories "are applicable"? My only guess is that it's a way of not quite committing to the positive statement. But is there really a difference? Is there some halfway state between applicable and not applicable (like being sort of pregnant)?