U.S. Supreme Court

Case Status


Docket Number


2014 Term

Lower Court Opinion


Questions Presented

Whether the United States Constitution prohibits a state from taxing all the income of its residents -- wherever earned -- by mandating a credit for taxes paid on income earned in other states.

Case Updates

U.S. Supreme Court says Maryland must provide full credit for taxes individuals pay on out-of-state income

May 18, 2015

The U.S. Supreme Court affirmed the Maryland Court of Appeals’ decision and held that Maryland’s tax rates for individuals violate the Commerce Clause by double-taxing certain income earned in other States. The Court reasoned that the economic effect of this double taxation was to impose a tariff on out-of-state investment, and that this tariff could not be justified by the amount of local services allegedly used by the taxpayer.

U.S. Chamber files amicus brief

September 26, 2014

In its brief, the Chamber asked the U.S. Supreme Court to affirm the decision of the Maryland Court of Appeals and invalidate Maryland’s tax scheme, which the brief argues, is inconsistent with the principles of interstate commerce that are protected by the Constitution’s Commerce Clause. The brief goes on to reason that Maryland’s tax scheme, which taxes its residents on income earned in other States but refuses to provide those residents with a full credit for the taxes paid to the other States, results in a failure to allocate taxes and therefore violates the Commerce Clause. The brief points out that the national economy is dependent upon the free movement of goods and services throughout the country; in order to prevent barriers to interstate trade, states must fairly apportion taxes which are levied on residents’ out-of-state income.

Jeffrey A. Lamken, Andrew R. DeVooght, and Gajan Sivakumaran of MoloLamken LLP represented the U.S. Chamber of Commerce as co-counsel to the U.S. Chamber Litigation Center.

Case Documents