There's a lot more to competence than a law degree and a modicum of courtroom skill.
We've made some mistakes in this country in times past - the Korean conflict proceeding that, some say proceeding the Persian Gulf War, where we were ambiguous as to what we would do.
For a long time in American history, people didn't even come up before the Senate. They didn't come before the Judiciary Committee, and up until about 1923, something like that.
That is, while we believe that cost-benefit analysis is an important tool to inform agency decision making, the results of the cost-benefit analysis do not trump existing law.