Abstract: There is a burgeoning literature on second opinions in professional contexts, as
when patients or clients seek advice from a second doctor or lawyer. My aim, by
contrast, is to analyze second opinions as a central feature of public law. I will try to
show that many institutional structures, rules and practices have been justified as
mechanisms for requiring or permitting decisionmakers to obtain second opinions;
examples include judicial review of statutes or of agency action, bicameralism, the
separation of powers, and the law of legislative procedure. I attempt to identify the
main costs and benefits of these second-opinion mechanisms, to identify conditions under
which they prove more or less successful, and to consider how the lawmaking system
might employ such mechanisms to greater effect. I claim, among other things, that
Alexander Bickel’s justification of judicial review as a “sober second thought” is
untenable, and that the Supreme Court should adopt a norm that two successive
decisions, not merely one, are necessary to create binding law.