The change is of a piece with regulatory practice in a number of contexts. The FDA itself sometimes requires a drug manufacturer that has received pre-market approval of its drug to conduct post-marketing studies, which can either confirm or cast doubt upon the initial judgment that the drug's benefits outweigh its risks. Likewise, in other specific contexts, the law either expressly requires periodic re-evaluation or regulates via an open-ended standard that itself has room for growth: E.g., a requirement that a device, drug or whatever be "safe and effective" would seem to require an updating of the baseline for both safety and effectiveness as technology improves. In this way, standards (rather than rules) sometimes automatically function as the sort of "best-practice" requirements that I discussed earlier in the week in my FindLaw column.
Nonetheless, regulation often occurs via fixed rules that have a limited capacity for re-evaluation and even best-practice standards can become dated over the course of a sufficiently long period of time. Perhaps the best example of these phenomena is the U.S. Constitution, whose essential features are so difficult to change that it operates in many respects like an outdated medical device, one that perhaps was justified many years ago but cannot be judged "safe and effective" today, given the alternatives (such as abolishing the Senate and the Electoral College, limiting Supreme Court tenure to 18 years, and you-name-your-pet-change).
Posted by Mike Dorf