There's no doubt congressional investigators have their hands full probing allegations the Internal Revenue Service targeted conservative non-profit groups. But now a different IRS scandal -- involving the chronic, ongoing, mind-bogglingly wasteful mismanagement of a popular tax credit program -- demands Congress's attention because it has taken on new importance with the arrival of Obamacare. The program is the Earned Income Tax Credit, through which the federal government gives out between $60 billion and $70 billion to low-income working Americans each year. It's known as a "refundable" tax credit, but it is basically a transfer payment, in which the IRS...