International traders may be confronted with regulations that appear to be neutral on their face but in fact affect imported products adversely. This disguised discrimination occurs in many forms. The most common form takes place through the application of technical regulations and product standards. While appearing to be neutral, these standards favor domestic products or industries. This form of discrimination is more difficult to attack under international trade rules, because there is usually a plausible explanation for the standards, such as health, environmental, safety, or standardization reasons. Internal taxation rules that are facially neutral can also favor domestic products over imports. In Schiefflin, the U.S. taxed distilled spirits at $10.50 per 'proof gallon' or 'wine gallon.' A proof gallon is a gallon of 100 proof spirits (50% alcohol by volume) whereas a wine gallon is a gallon of below 100 proof spirits. The tax was due where the spirits were withdrawn from bond, either a bonded warehouse or a customs bond. U.S. distillers could withdraw the spirits from bond in bulk (and pay $10.50 per proof gallon), prior to dilution below 100 proof and bottling. Since U.S. producers typically