Legislative oversight is not a specifically enumerated power in the Constitution — it’s a limited power implied from the “necessary and proper” clause and subject to privileges, separation of powers, and the need for a legitimate legislative purpose. It’s not an open-ended power but bounded by the checks and balances of our constitution.
The Mueller report should have closed down investigations of the president, not opened them up. It unambiguously cleared the president of any conspiracy or collusion with the Russians, ending two or more years of undermining the president and his family with unfair and unjust criminal investigations. There is nothing more distracting for an administration than to be under independent counsel investigation and I should know, I was there in 1998 when President Clinton was impeached.
Instead, Nadler‘ s response has been to begin a coordinated plan with other Democratic committee chairs to subpoena every tax, business and other records of the president, his family, and his businesses and associates.
Now that kind of inquisition is exactly what dictators do, especially when they are trying to use their power to destroy their political opponents.
There is not a smidgen of bipartisanship in any of his actions and so the precedent it sets could be the most destructive congressional behavior since Joe McCarthy discovered he could use and abuse the investigative process for political gain.
By comparison, McCarthy was a piker.