To understand the moral context of the IRS' admission that it improperly targeted conservative Tea Party and Patriot nonprofits during the 2012 presidential campaign, it helps to know that Richard Nixon, Bill Clinton and Barack Obama have something in common besides twice being elected to the Oval Office: All three appear to have been quite willing to use the most intrusive powers of the federal government against their political opposition.

Nixon was especially craven about it. He made clear to aides that they were to use the IRS against Democratic nominee George McGovern, senior members of McGovern's campaign staff and major Democratic National Committee donors in the 1972 campaign: "What in the name of God are we doing on this one? What are we doing about the financial contributors? ... Are we looking over the financial contributors to the Democratic National Committee? Are we running their income tax returns?" Nixon ordered Treasury Secretary George Schultz to "just do it" and the returns of McGovern and many of his key supporters were delivered to the Nixon campaign. From such ethically challenged operators came Watergate.

Two decades later, it was Filegate, which Clinton famously said was nothing more than "a completely honest bureaucratic snafu" when FBI security-clearance files on at least 400 prominent Republicans somehow turned up at the White House. Multiple investigations subsequently failed to show whether Clinton or first lady Hillary Clinton ordered senior aide Craig Livingstone to request the files from the FBI. Even so, Clinton's dismissal of the scandal as a bureaucratic foul-up is hard to square with the fact Livingstone's only qualification for the job of director of White House personnel security was his work as an advance man for the 1992 Clinton-Gore campaign and other Democratic campaigns.

Unlike the Nixon scandal, there is as yet no evidence that Obama or one of his top aides ordered the IRS to go after the conservative groups, but then it was only on Friday that Lois Lerner, who heads the IRS tax exemption unit, admitted the "inappropriate" actions while answering a question during an American Bar Association conference. Those actions were committed by low-level employees in the Cincinnati IRS office, Lerner claimed. The most interesting immediate question may be what prompted Lerner's unexpected candor about an issue that has been percolating since last summer when Tea Party groups across the country first reported receiving demands from the tax agency for copies of their donor lists.

Those reports sparked an investigation by the Treasury Department's inspector general for tax administration. Maybe it's merely coincidental that the IG is expected to release a report on the issue next week. Or could it be that Lerner got an advance peek at that report and her admission was an attempt to get ahead of the spin on its conclusions?

House Ways and Means Committee Chairman Dave Camp, R-Mich., said "the IRS absolutely must be nonpartisan in its enforcement of our tax laws. We will hold the IRS accountable for its actions." That's fine, Mr. Camp, but the highest priority is finding out who authorized the dirty work, regardless of whether they work at the IRS.