Conservatives and liberals have long debated the most effective way to ensure accountability in government. Conservatives, who usually view human nature as inherently flawed, automatically distrust those exercising official power. Liberals, for whom the perfectibility of man is an article of faith, argue that government is inherently benevolent -- and that officials who would abuse their power are restrained by the threat of exposure.

Attorney General Eric Holder certainly did not intend to resolve that discussion one way or the other, but he may have inadvertently done so when he allowed a trusted subordinate to approve the Justice Department's subpoena of a massive collection of Associated Press telephone records. The subpoena covered 20 telephone lines, which were used by legions of AP reporters, editors and executives, over a two-month period. That included thousands of calls, many undoubtedly involving conversations between reporters and sources.

The damage to the AP's ability to report the news could be incalculable, since sources inside and outside government must now wonder whether their past dealings with the news organization were secure and whether it's worth gambling that future conversations won't be similarly compromised. Even if the Justice Department apologizes to the AP, there are no guarantees that the breach won't happen again with the same or a different news organization under the current or a future president.

Defenders of broad government authority rightly point out that Justice Department regulations narrowly circumscribe the conditions under which federal officials can subpoena information, testimony or documents from the news media. The AP subpoena shows, however, that tightly written regulations cannot always block a determined official, even when that official serves a president who promised "the most transparent administration ever." This is why the Federalist Papers warned that "parchment barriers" would not always suffice to limit government power or ambitious mandarins. The conservative approach -- don't let government issue such subpoenas in the first place -- would not always prevent abuses either, but at least there would be no room for arguments about how many media exceptions the government can dance on the head of a regulatory pin.

Note that the AP subpoena story broke soon after the IRS harassment of Tea Party groups was exposed and President Obama dismissed the Benghazi talking points firestorm as a mere "political sideshow." This trio of scandals are not strangers to one another. Government that violates the news media's constitutionally guaranteed independence cannot be expected faithfully to follow laws mandating transparency in official operations. Abuses of power and misrepresentations about government operations and those responsible for them are the inevitable result.

George Washington warned about this in his farewell address: "The spirit of encroachment tends to consolidate the powers of all the departments in one, and thus to create whatever the form of government, a real despotism. A just estimate of that love of power, and proneness to abuse it, which predominates in the human heart is sufficient to satisfy us of the truth of this position." In other words, it is unwise to expect unalloyed virtue from Big Government.