This note concerns the decision of the US Court of Appeals for the Federal Circuit in the National Westminster Bank (NatWest) case regarding US interest deductions for 1981 to 1987. The case involved Art. 7 (Business profits) of the 1975 UK-US income tax treaty and the application of the US branch interest rules of US Treasury Regulation Par. 1.882-5. The US Court of Appeals upheld the opinions of the US Court of Federal Claims that the US Treasury Regulation violated Art. 7.