At the same time the IRS harassed Republican nonprofit groups during the 2012 political campaign, it selectively advised black churches and other Democrat nonprofits on how far they can go in campaigning for President Obama and other Democrats. This raw exercise in political favoritism has not been reported in the context of the still-smoldering IRS scandal, in which the agency in 2012 audited big GOP donors and blocked Tea Party groups trying to obtain tax-exempt status as part of what House investigators suspect was an effort to re-elect the president. But that same year, top officials with both the IRS...