The Internal Revenue Service has found itself at the other end of an audit, and rightly so. The recent revelation that the agency targeted conservative groups for heightened scrutiny raises the specter of misuse of one of government's greatest powers - taxation - for political purposes.

Starting in early 2010, as a conservative backlash against the Obama administration was growing, IRS officials began paying special attention to applications for tax-exempt status from groups with names including the words "tea party" and "patriot," according to documents from an internal investigation obtained by the Washington Post. Tax officials also flagged other typically right-wing terminology, such as "take back the country" and "9/12," a date often cited by the conservative commentator Glenn Beck.

While many questions remain about the motives and origins of the policy, the mere existence of such a clearly politically biased directive richly deserves the increasingly bipartisan condemnation it's received. Sen. Susan Collins of Maine, a moderate Republican, feared it would encourage "the profound distrust that the American people have in government." President Obama joined the criticism Monday, noting the need for "absolute integrity" at the IRS.

The agency appears to have been grappling with a sudden proliferation of applications to form tax-exempt "social welfare" groups. The Supreme Court's 2010 Citizens United ruling held that such groups can engage in political activity as long as campaigning is not their primary purpose.

Apparently in response to the concerns of ranking IRS officials, the criteria for scrutiny of those groups were revised several times over the next two years. While some of the revisions approached political neutrality, others raise additional concerns about the agency's goals. For example, the IRS decided at one point to look more closely at groups interested in "limiting/expanding government" or "educating on the Constitution and Bill of Rights."

The full report of the agency's inspector general has yet to be released, and further investigation is inevitable and warranted. But even if the IRS was attempting to respond to a legitimate policy problem, it seems to have done so in a way that was at best ham-handed and at worst abusive. Some constitutional education may be in order after all.