Asking what role people’s preferences should play in poli- cies regarding the return of biobank research results is a specif- ic case of asking what role facts should play in prescriptions governing action. Since Scottish Enlightenment philosopher David Hume articulated the point, it has been generally recog- nized that one cannot derive an “ought” from an “is.”‘ Nevertheless, it is also generally and correctly assumed that facts matter for prescriptions. They occasion or motivate the development of policy as, for example, the revelation of Nazi atrocities committed in the name of research-motivated the de- velopment of the Nuremburg Code. They also constrain policies as prescriptive guides to action are constrained by what is actually, factually possible-”ought” implies or assumes “can,” as philosophers say.2 And, they inform policy as when facts about burdens of various research protocols, for example, are used to develop criteria for assessing an appropriate balance of burdens and potential benefits. Finally, a primary point of ethical, legal, and regulatory prescriptions is to protect and promote the interests of people and to fulfill their needs. Facts about those interests and needs are therefore fundamentally relevant to policy development. Moreover, if in fact no one actually embraced a particular prescriptive policy, there would be no will to follow or enforce it.