The IRS denies having conducted a partisan witch-hunt against tea-party groups in the run-up to the 2012 election, arguing that its improper targeting of conservative groups was the result of a series of procedural errors rather than a political attack with malice aforethought.But the IRS is keeping the relevant evidence secret, so you will just have to take the agency’s word for it.Lois Lerner, the IRS official in charge of handling tax-exempt organizations, made what appeared to be an impromptu confession Friday during a tax conference hosted by the American Bar Association, saying that groups with the words “tea...