Behold the subpoena power in an opposition Congress.
It's gratifying to see Congress finally exercising its constitutional responsibilities of oversight after six years of rubber-stamping the dubious practices of the George W. Bush administration. Now that Congress is controlled by the opposition, Bush and the Gang That Couldn't Shoot Straight are no longer able to operate under cover of political darkness. As a result, we see Congress properly exercising its subpoena power in order to get to the bottom of such abuses like the politically-motivated firings of federal prosecutors, the mismanagement at Walter Reed, and the FBI's excessive use of security letters in infringing Americans' civil liberties.
In an ideal world, we hope that elected officials in both the executive and legislative branches will view honoring their sworn obligation to faithfully uphold the Constitution as their preeminent responsibility, rather than allowing those obligations to take a back seat to politics; but all too often that seems not be the case - instead, politics are allowed to prevail.
The danger of factions (e.g., political parties) was recognized by Madison and others from the nation's beginnings (though, ironically Jefferson and Madison later became instrumental in the development of political parties), and we've seen this play out throughout American history into modern times with the extreme political partisanship that we witness today. Hence the importance of checks and balances among the political branches - such as Congress's subpoena power - to neutralize the corrosive effects of faction.
