It was pretty much agreed by the Founders that it was not acceptible to impeach for "political" reasons because the Court was considered outside of politics.
This is false. The founders viewed congressional impeachment of judges as a perfectly legitimate political exercise against judges who make law from the bench, or who apply the law in a way is contrary to Congressional/legislative intent.
This doctrine was taken so seriously that Congress would not even remove an insane alcoholic judge, Pickering I believe, early in the Republic's history.
Removal of a judge for mental incompetence (e.g., insanity, drug-induced rulings, etc.) has no probative value to the question of whether or not impeachment is legitimately a political process. By the way, Pickering was removed.
Chase actually could have been removed legitimately because his behavior on the bench was abusive and biased IMO.
Chase's judicial appointment survived impeachment because Congress voted along political lines. This is contrary to the view that impeachment proceedings are not political in nature. There is little doubt that Chase's decision was the wrong one, the law was misapplied. Even Chase's defenders admitted as much. But Chase was not removed. The person(s) conviced in Chase's court were pardoned.
President Thomas Jefferson, leader of the Republicans, disliked the idea of judges being appointed for life. He feared that under such a system, the judiciary might become too powerful. And when Samuel Chase expressed Federalist opinions from the bench, Jefferson encouraged the House of Representatives to impeach him.So, a founder, Jefferson, encourages Congress to impeach a Supreme Court justice for what amounted to politically motivated court orders. This is a concrete example against the statement, "It was pretty much agreed by the Founders that it was not acceptible to impeach for 'political' reasons because the Court was considered outside of politics."
A question then is what constitutes "political" activity? I think legislating from the bench fits that, nicely. As does thumbing the judicial nose, showing the judical ass, to Congress.
Do I think Congress has the political will to override an activist judiciary? Nope. We're stuck with activist courts. The GOP-lead Congress doesn't have the balls to use it's Constitutionally granted power of impeachment. Heck, the GOP-lead Congress doesn't seem to have the balls to approve presidential appointments.
When the Founders wrote the Constitution they believed one of the greatest dangers the Nation faced was "factions" and strove to avoid them and their partisianship. It was in that sense that the Court was considered non-political unaffected by partisian bias.
The virtual absence of political impeachments of judges since that time is evidence that this interpretation is still operative. Nixon's certain impeachment and conviction is an example of the process being above politics. It was an operation of both parties. Clinton's was an example of politics intruding and stopping the process. Jefferson unwisely and unsuccessfully attempted to make the Chase case political. This caused the Federalists to rally around him.
Jefferson is not considered a Founder in the strict sense since he was not a member of the Constitutional Convention and his understanding of the document is suspect at best and completely unworkable at worst. His attempt on Chase is evidence that the political motivation of an impeachment was not acceptable at least at that time. I admit that the Founders' idealism that the courts stay outside of politics and the Congress avoid it wrt impeachments may be too optimistic or mistaken.