Manuel Balce Ceneta, AP
Tea Party supporters gather for a rally outside the IRS headquarter in Washington, May 21, 2013. A few dozen tea party activists and their supporters have gathered outside the IRS headquarters in Washington to protest extra scrutiny of their organizations. (AP Photo/Manuel Balce Ceneta)

No federal agency is more despised than the Internal Revenue Service. Each year, we are required by federal law to submit our personal finances to the IRS for review. It is never a pleasant process. With a tax code that is ever changing and longer than the collective works of William Shakespeare, most Americans pay professionals to help them prepare their taxes. Even with such help, each of us knows that at any moment the IRS can knock on our door and turn our lives upside down.

We have all witnessed dozens of political "scandals" over the years. This has happened so often that we almost exclusively associate the word with politics. A few such incidents stick in our minds (who can forget Nixon's revelatory statement that "I'm not a crook" or Clinton's argument that whether or not he lied under oath depended on what the "meaning of the word 'is' is"?). While all political misdeeds strain the tenuous trust between the people and the government, not all scandals are equal. Some scandals can cause permanent damage to our social compact.

The recent revelation that the IRS harassed and intimidated groups based on their political leanings is the worst kind of scandal — it is an assault on our founding charter itself. Of all the principles upon which we built this country, none is more important than equal protection under the law. As Americans, we must speak with one voice and insist on complete transparency into the origins of this breach of public trust. In the words of the Greek philosopher Epictetus, "The people have a right to the truth as they have a right to life, liberty and the pursuit of happiness."

Here is what we know: The IRS field office in Cincinnati houses a Determinations Unit, which is responsible for overseeing requests for tax-exempt status. Beginning in March 2010, the unit began subjecting applications for tax-exempt status from conservative groups to enhanced scrutiny. While applications from liberal leaning groups sailed through the approval process, the Determinations Unit subjected conservative groups to accusatory questionnaires and egregious delays.

This process was implemented with the full knowledge and encouragement of Lois Lerner, director of the Determinations Unit. In July 2010, Lerner instructed her staff to be on the lookout for applications from groups that would oppose President Obama or agitate for smaller government. While Lerner and her posse suspended this practice in mid-2011, they started up again in early 2012 just as the election season started heating up.

In March 2012, after numerous complaints, Congress questioned then-IRS commissioner Doug Shulman about the IRS' behavior. Shulman denied that the IRS was targeting groups based on their politics. Two months later, the Determinations Unit revised and neutralized its screening criteria. Finally, in June 2012, Congressman Darrell Issa formally requested an audit of the Determinations Unit by the U.S. Treasury Inspector General for Tax Administration (TIGTA).

Two weeks ago today, in anticipation of the release of the TIGTA audit, Lerner decided she could no longer keep the scandal hidden. In response to a planted question after some remarks at the American Bar Association, Lerner apologized for the "inappropriate" targeting of conservative groups.

Lerner's admission has unleashed a firestorm of indignation from Democrats and Republicans alike. While Lerner's behavior was clearly biased by her own political beliefs, I am pleased to see that our leaders in Washington recognize that this is not a partisan issue. I hope Congress will work together to get to the bottom of this scandal. We need them to.

Dan Liljenquist is a former state senator and U.S. Senate candidate.