As a glutton for punishment I'm reading that book. One chapter discusses the Mueller investigation in the context of special prosecutors and the criminalization of oversight. The authors ding Congress for lack of effective oversight, instead ceding oversight to the criminal process of investigations through the special prosecutors.
I wonder if Congress shouldn't delegate its oversight powers to an agency set up like GAO. GAO works for Congress, not the executive, and has a good reputation, I think, unless you're a bureaucrat being critiqued. But GAO focuses on the bureaucracy and on policy, worrying whether the laws Congress passes are being effectively administered by the executive branch. It's my impression they rarely interview the big shots, the presidential appointees, and never those close to the president. I'm not sure why; whether it's historical precedent or their legal charter at work.
The problem I see with my idea is that it seems like the old special prosecutor--giving a body authority to investigate without establishing limits. That problem led to both parties agreeing not to reauthorize the statue which existed for about 20 years.
Maybe we could look to the Congressional ethics committees, which police the members of Congress? Maybe a standing bipartisan committee could work, relying on political forces to restrain it? The problem there might be shown in the Federal Election Commission, which is supposed to be bipartisan but has been deadlocked with vacancies for years.
No answers here.