Mr. Summers's reputation is replete with evidence of a temperament unsuited to lead the Fed. He is known for cooperation when he works with those he perceives as having more power than he does, and for dismissiveness toward those he perceives as less powerful. Those traits would be especially destructive at the Fed, where board members and regional bank presidents all bring their own considerable political power and intellectual heft to the Fed's decision-making on monetary policy and financial regulation. Putting Mr. Summers in charge would risk institutional discord or worse, dysfunction.His record on financial regulation is abysmal, and he has not acknowledged the errors. In the late 1990s, Mr. Summers was instrumental in deregulating derivatives and in repealing the Glass-Steagall banking law. He has said that the resulting financial crisis was unforeseeable, which is wrong. He waged public battles against regulators who correctly argued for regulating derivatives and disparaged thecomments of a prominent economist who early on identified risks in the too-big-to-fail banking system. This is precisely the wrong background for the next Fed leader, who will take charge in the middle of the delayed rule-making for the Dodd-Frank financial reform law.