Robert Loblaw has this interesting report on Haver v. Commissioner, 05-1269 (D.C. Cir., 4/11/06):

In this tax appeal, the D.C. Circuit is called upon to resolve alleged discrepancy between an international tax treaty and the U.S. Tax Code. Peter Haver is a U.S. citizen who lived and worked in Germany for three years. Because the German taxes he paid exceeded his U.S. tax liability, he claims that he does not owe any taxes. The IRS disagreed on the ground that Haver still owed the Alternative Minimum Tax. The treaty at issue allows U.S. citizens who pay German taxes to claim the amount paid as a credit on their U.S. taxes, "subject to the limitations of the law of the United States." Based on this latter phrase, the D.C. Circuit concludes that there is no conflict between the treaty and the AMT, so Haver will be required to pay U.S. taxes as well.