Sen. David Vitter (R-La.) has a simple question: How and why did Congress qualify as a “small business” eligible for special taxpayer subsidies under the Affordable Care Act (ACA)? For anyone in a real small business — private employers who get no such subsidies — the very idea is absurd. But getting a straight answer is as difficult as getting Lois Lerner’s IRS emails.

In search of answers, Vitter proposed subpoenaing documents from the District of Columbia Health Benefits Exchange Authority. But his colleagues on the Small Business and Entrepreneurship Committee recently voted (14 to five) to block the effort. They’ve tried to justify their lack of curiosity by calling the proposed subpoena an unnecessary “distraction” or an invitation to a “protracted” legal fight. But these are rather obviously lame excuses.