Calls to regulate or restrict scientific research are often a matter of politics, and public desire to regulate science may have its source in several different underlying interests: on one side, people may be motivated by an interest to control risks, prevent harms, or limit access to powerful or dangerous technologies. These interests are easy to understand, and often provide entirely appropriate and creditable grounds for regulation. In a darker vein, people may be motivated by more general mistrust of science, or by moral or religious disapproval of some kinds of research. While these motives may be easy to understand, clearly they should be resisted. But if researchers hope to avoid inappropriate regulations, we need to be prepared to explain our research to the public. And when research is funded by tax dollars, it is especially important that scientists should be able to justify its benefit to taxpayers and legislators.