The working hypothesis for the tariff negotiations was a linear tariff cut of 50% with the smallest number of exceptions. A drawn-out argument developed about the trade effects a uniform linear cut would have on the dispersed rates (low and high tariffs quite far apart) of the United States as compared to the much more concentrated rates of the EEC which also tended to be in the lower held of United States tariff rates.
The EEC accordingly argued for an evening-out or harmonization of peaks and troughs through its cerement, double cart and thirty: ten proposals. Once negotiations had been joined, the lofty working hypothesis was soon undermined. The special-structure countries (Australia, Canada, New Zealand and South Africa), so called because their exports were dominated by raw materials and other primary commodities, negotiated their tariff reductions entirely through the item-by-item method.
In the end, the result was an average 35% reduction in tariffs, except for textiles, chemicals, steel and other sensitive products; plus a 15% to 18% reduction in tariffs for agricultural and food products. In addition, the negotiations on chemicals led to a provisional agreement on the abolition of the American Selling Price (ASP). This was a method of valuing some chemicals used by the noted States for the imposition of import duties which gave domestic manufacturers a much higher level of protection than the tariff schedule indicated.
However, this part of the outcome was disallowed by Congress, and the American Selling Price was not abolished until Congress adopted the results of the Tokyo Round. The results on agriculture overall were poor. The most notable achievement was agreement on a Memorandum of Agreement on Basic Elements for the Negotiation of a World Grants Arrangement, which eventually was rolled into a new International Grains Arrangement.
The EEC claimed that for it the main result of the negotiations on agriculture was that they "greatly helped to define its own common policy". The developing countries, who played a minor role throughout the negotiations in this Round, benefited nonetheless from substantial tariff cuts particularly in non-agricultural items of interest to them.
Their main achievement at the time, however, was seen to be the adoption of Part IV of the GATT, which absolved them from according reciprocity to developed countries in trade negotiations. In the view of many developing countries, this was a direct result of the call at UNCTAD I for a better trade deal for them.
There has been argument ever since whether this symbolic gesture was a victory for them, or whether it ensured their exclusion in the future from meaningful participation in the multilateral trading system. On the other hand, there was no doubt that the extension of the Long-Term Arrangement Regarding International Trade in Cotton Textiles, which later became the Multi-Fiber Arrangement, for three years until 1970 led to the longer-term impairment of export opportunities for developing countries.
Another outcome of the Kennedy Round was the adoption of an Anti-dumping Code, which gave more precise guidance on the implementation of Article VI of the GATT. In particular, it sought to ensure speedy and fair investigations, and it imposed limits on the retrospective application of anti-dumping measures.