The <a href="https://en.wikipedia.org/wiki/European_Court_of_Justice" id="mw5w" rel="mw:WikiLink" title="European Court of Justice">European Court of Justice</a>'s ruling in <i id="mw6A"><a href="https://en.wikipedia.org/wiki/Van_Gend_en_Loos_v_Nederlandse_Administratie_der_Belastingen" id="mw6Q" rel="mw:WikiLink" title="Van Gend en Loos v Nederlandse Administratie der Belastingen">Van Gend en Loos v Nederlandse Administratie der Belastingen</a></i> establishes the principle of <a href="https://en.wikipedia.org/wiki/Direct_effect_of_European_Union_law" id="mw6g" rel="mw:WikiLink" title="Direct effect of European Union law">direct effect</a>, one of the most important, if not the most important, decisions in the development of <a href="https://en.wikipedia.org/wiki/European_Union_law" id="mw6w" rel="mw:WikiLink" title="European Union law">European Union law</a>.