The Lesser Duty Rule is that the amount of the anti-dumping duty shall not exceed the margin of dumping established but it should be less than the margin if such lesser duty would be adequate to remove the injury to the Union industry. So the second sub-principle of the principle of proportionality, the principle of necessity is well given body to the Lesser Duty Rule in the EU Anti Dumping Law.But it is the problem whether the EU’s method in assessing the margin of injury i.e. setting up of target price, transaction to transaction method, negative zeroing in applying the Lesser Duty Rule is violating the principle of fair comparison in the WTO Anti Dumping Agreement or not. That is why the most important criteria in the calculation of amount of injury is not written in the Basic Regulation 2016/1036.The reason why is that firstly, the method of calculating the reasonable profit on the basis of target price while assessing the dumping margin by price underselling margin is always higher than the real price and leads to the EU institution’s arbitrary decision.Secondly, we don’t know the detailed grounds on the reasonable profit rate because the reasonable profit rate achievable without dumping products is stated in anti dumping regulation imposed by the European Commission but the detailed grounds on the reasonable profit rate is not in the regulation.Thirdly, the Court of Justice of European Union does not rule the concrete criteria about the reasonable profit in calculating the injury margin too.Fourthly, since EC-Cotton-Type Bed Linen from India case, EU does not do zeroing in calculating the dumping margin. But EU does zeroing in calculating the injury margin by model zeroing method.But it is not violating the WTO’s rule. The reason why is that if the injury margin is less than the dumping margin, the Commission is allowed to impose anti dumping duty the full margin of dumping or less under the WTO Rule.Ultimately, norms and standards shall be arranged in WTO level to find the reasonable method in calculating injury margin.