In the wake of any new law, predictions come fast and furious--see Megan, Ezra, Megan, etc. Many are interesting and serve as useful devices for thinking about the new law's effects. I myself lack the powers of foresight to proclaim, as Megan does, an 80 percent chance of there being pharmaceutical price controls twenty years hence (if I had such powers they'd be directed toward sports betting). I'm just as curious about what happens, but I'm instinctively skeptical that anybody can know. What seems most important often turns out not to be.

To take just one recent example, a year ago the centerpiece of the Obama administration's response to the financial crisis was thought to be the Public-Private Investment Program (PPIP). This is the controversial program that let private investors put up a small sum, combine it with a much bigger sum from the government (which also guaranteed the transaction), and purchase the toxic assets hampering banks' balance sheets, thereby--the thinking went--easing the crisis. An awful lot was written about this at the time. I haven't looked, but I predict that if I did go look I'd find that most of the predictions about the response plan centered on the PPIP. But as I write in the current Atlantic, it was Tim Geithner's stress tests, and not the PPIP, that rather unexpectedly turned out to be the key to the government's response. So you can never really know.

The flip side of this is that seemingly minor provisions can wind up having major effects. Often, these are the results of compromises or even lost battles, something settled for when larger changes can't be won. My favorite example is something called the Toxic Release Inventory, which sprung from the failed effort to regulate airborne pollutants in the mid-1980s. At the time, clean air legislation, like health care today, was bitterly contested. Proponents thought there was a lot of pollution in the air, and that it posed a serious health threat; opponents claimed there wasn't. A 1985 bill to regulate airborne pollutants was considered a failure when it was stripped of everything but the Toxic Release Inventory, which simply established that pollution would be measured. A few years later, the inventory disclosed its first results: there was 25 times more pollution in the air than anyone had imagined. This revelation helped bring about the last law on the scale of health care reform, the 1990 Clean Air Act. In their book "Nudge," Richard Thaler and Cass Sunstein dub the TRI "the most unambiguous success story in all of environmental law."

There's a provision in the new health care law that strikes me as intriguingly similar to the TRI, and that's the Physician Payments Sunshine Act, which establishes that doctors must reveal payments from drug companies. We already know, primarily from a series of articles in the New England Journal of Medicine, that this troubling practice has been going on for some time. Someday soon, we'll know how widespread it is. I'm not going to predict that it will turn out to be much more than anyone imagines, anymore than I'm going to wager my hard-earned money on Cornell making it to the Final Four. But I'll be watching both with interest.