Amministrazione delle Finanze dello Stato v Simmenthal SpA  ECR 629 is also known as C-106/77 Simmenthal (1978). It is a European Union case concerning Supremacy of EU Law.
A French beef importer had to pay a fee for inspection when it imported its beef into Italy. As a result, the importer argued that Italian Law (1970) was passed after EU provisions came into force in 1964 and 1968. Therefore, it prevailed.
Therefore, the respondent (meat company) argued that tax fees on the imports of beef at the Italian border were incompatible with the EU law.
Were the charges (tax fees) allowed to be made (against EU law)?
In conclusion, it was held in the Simmenthal case that these charges were incompatible with EU law and contrary to the Treaty. Therefore, the Court of Justice of the European Union ruled that national law must protect EU law. Domestic law must apply EU law in its entirety and disregard national law that may conflict with it.
Under the principle of Supremacy, there is a duty to set aside conflicting domestic laws. Moreover, Eu Law is not relevant in domestic law however, because the imported meat crossed borders, EU Law on the Free Movement of Goods applies. The inspection fee is an Italian provision.
Reaffirms: Costa v Enel
References: C-106/77, R-106/77,  EUECJ R-106/77,  ECR 629,  3 CMLR 263