Final answer:
The justifiability of Dutch authorization requirements as MEQR depends on the scientific basis for the safety standards and if they are applied without discrimination among countries with identical or similar conditions. If the standards are to ensure safety and do not unfairly discriminate, they could be justified.
Step-by-step explanation:
Whether Dutch authorization requirements for the sale of sport supplement products are justifiable as Measures Equivalent to Quantitative Restrictions (MEQR) depends on the underlying reasons for these requirements. Based on the WTO rules and principles, it is legitimate for a country to impose safety standards on imported goods, provided that there is a scientific basis for such standards and they do not arbitrarily or unjustifiably discriminate between countries where identical or similar conditions prevail. In the case of the Dutch authorizations, if the requirements are to ensure consumer safety and are applied equally to both domestic and imported products, without unfair discrimination among countries, then the measures could be seen as justifiable. However, if these regulations are more stringent than the standards recognized by other European countries without a scientific justification, they could be viewed as disproportional and thus unjustifiable.