There is a long history of states using tax systems to encourage residents to invest in bonds issued by jurisdictions within their state. This preferential or discriminatory tax treatment was ruled unconstitutional in 2006 by the Kentucky Court of Appeals. The Kentucky court decision, which sets the stage for this essay, was overturned by the U.S. Supreme Court in 2008. This essay addresses the possible implications of this and similar discriminatory tax policies. Such discriminatory policies are the foundation of the municipal bond market, and altering the practice would have significant implications for revenue collections and borrowing costs in most states and localities. While the Supreme Court's position has been rendered, the case has caused policy makers and administrators to scrutinize discriminatory tax policies and their impact on budgets and borrowing costs.