121. In the present case, the Court observes that the notification toArgentina of the environmental impact assessments for the CMB (ENCE)and Orion (Botnia) mills did not take place through CARU, and thatUruguay only transmitted those assessments to Argentina after havingissued the initial environmental authorizations for the two mills inquestion. Thus in the case of CMB (ENCE), the matter was notified toArgentina on 27 October and 7 November 2003, whereas the initialenvironmental authorization had already been issued on 9 October 2003.In the case of Orion (Botnia), the file was transmitted to Argentinabetween August 2005 and January 2006, whereas the initial environmentalauthorization had been granted on 14 February 2005. Uruguay oughtnot, prior to notification, to have issued the initial environmental auth-orizations and the authorizations for construction on the basis of the envi-ronmental impact assessments submitted to DINAMA. Indeed by doingso, Uruguay gave priority to its own legislation over its proceduralobligations under the 1975 Statute and disregarded the well-establishedcustomary rule reflected in Article 27 of the Vienna Convention on theLaw of Treaties, according to which “[a] party may not invoke the pro-visions of its internal law as justification for its failure to perform atreaty”.