FLASHBACK: You Are Probably Breaking The Law Right Now.

Ignorance of the law, we are often told, is no excuse. “Every man is presumed to know the law,” says a long-established legal aphorism. And if you are charged with a crime, you would be well advised to rely on some other defense than “I had no idea that was illegal.”

But not everybody favors this state of affairs. While a century or two ago nearly all crime was traditional common-law crime — rape, murder, theft and other things that pretty much everyone should know are bad — nowadays we face all sorts of “regulatory crimes” in which intuitions of right and wrong play no role, but for which the penalties are high.

Unless you’re a government official, of course, in which case you get qualified immunity for breaking the law unless it’s “clearly established.”