Such a presumption might seem unfair, and indeed this kind of presumption seemed very unfair to the Supreme Court for a few years back in the 1970s. But as the Supreme Court came to realize upon further reflection, an irrebuttable presumption is little different from any other legal rule. Yes, the possessor of 28 grams of cocaine might not be a drug dealer, but the person who drives at 70 miles per hour in a 55-miles-perhour zone might not be driving unsafely, and the insider who buys and then sells shares in her own company in a less-than-six-months period may not be in possession of any inside information at all. But, as we saw in Chapter 2, rules do their work precisely by cutting off access to their background justifications, and few are surprised that exceeding the speed limit while driving very safely is still an invitation to a traffic ticket.

Unknown, Frederick Schauer - Thinkin…, loc. 417