Against the background of the aim to reach a level playing field through international trade liberalisation to be implemented in the sensitive policy fields of immigration and the labour market, this contribution will discuss the difference in effect on, and implementation of, European Union and World Trade Organization law in the national legal order. Taking the Netherlands as an example, international liberalisation resulting from the European Union on the one hand and the World Trade Organization on the other and the resulting Dutch policy for the admission of third-country nationals will be examined. For comparative reasons, this article will concentrate on third-country nationals working as posted employees of service suppliers. This examination will reveal the type of measures used to regulate access for third-country nationals to the Dutch labour market and the restrictive effect the two treaties have on these measures. Emphasising the contrast between positive rhetoric surrounding the migration-development nexus and the reality of restrictive immigration policies, the contribution will address the tension that exists between trade liberalisation on the one hand, and national immigration and labour market policies on the other. The contribution will conclude with an overview of underlying reasons on which this tension is based.