As is well known in federal securities law scholarship, one of the major goals of law and regulation in this area is to protect retail investors. In the most basic sense, legal mandates should tell financial professionals like brokers1 to avoid practices harmful to those investors and to put the interests of investors before their own. Regulations often have to be detailed because they must address already identified harmful practices and anticipate others. Recently implemented Regulation Best Interest (Reg BI) is a good example of this kind of detailed regulation insofar as it both establishes duties of brokers to retail investors and, in particular and among other things, compels firms to disclose, mitigate, or eliminate conflicts of interest of the broker-dealer and brokers that could lead them to put their interests above those of investors.2