by Paul Bertorelli

Forty years ago, struggling to attach a definition to the slippery concept of obscenity, Justice Potter Stewart famously demurred. But he coined a catchphrase that’s with us still: “I know it when I see it.” Although the justice was referring to racy magazines sent through the mail, he could just as well have been talking about our torturous attempts to pin down another vaporous concept: defining risk. Like Stewart, most of us know it when we see it but everyone sees it differently. …