"So if we stick with the assumption that government acts non-arbitrarily and in the public interest, then tax “loopholes” are as legitimate a part of the fiscal bargain between voters, taxpayers, interest groups, and politicians as are determinations of the tax base and tax rates themselves."

From "On the Legitimacy of Tax Loopholes" at: 
http://cafehayek.com/2012/04/on-the-legitimacy-of-tax-loopholes.html