POSSIBILITIES OF DEROGATION , THE MEASURES WHICH MIGHT BE TAKEN IN CASES OF EXCEPTIONAL DIFFICULTY AND THE SETTLEMENT OF DIFFERENCES BETWEEN THE CONTRACTING PARTIES . THE SAME CONSIDERATIONS APPLY TO THE ARTICLES CITED BY THE CORTE SUPREMA DI CASSAZIONE .
24 SO FAR AS THE TARIFF PROTOCOLS CONCLUDED IN THE FRAMEWORK OF GATT ARE CONCERNED , IT SHOULD BE NOTED THAT THOSE PROTOCOLS ARE CHARACTERIZED BY THE FACT THAT THEY REFER , IN THE TARIFF SCHEDULES ANNEXED THERETO , TO THE CUSTOMS TARIFFS OF THE PARTIES CONCERNED . THEREFORE THOSE PROTOCOLS CAN , BY VIRTUE OF THEIR GENERAL SCHEME AND ALSO OF THAT OF GATT , BE EFFECTIVE ONLY THROUGH THE INTERMEDIARY OF THE CUSTOMS TARIFF OF THE CONTRACTING PARTIES AND THUS , IN THIS CASE , THROUGH THE INTERMEDIARY OF THE COMMON CUSTOMS TARIFF .
25 HOWEVER , A SPECIAL SITUATION EXISTED AT THE TIME WHEN THE CONTESTED CHARGES WERE LEVIED INASMUCH AS THOSE CHARGES WERE FOR THE MOST PART LEVIED BEFORE THE INTRODUCTION OF THE COMMON CUSTOMS TARIFF ON 1 JULY 1968 . IT IS THEREFORE NECESSARY TO CONSIDER SEPARATELY THE PERIODS BEFORE AND AFTER 1 JULY 1968 .
26 SINCE DIRECT EFFECT CANNOT BE ATTRIBUTED TO THE TARIFF PROTOCOLS IN QUESTION OR TO THE PROVISIONS OF GATT WHICH DETERMINE THE EFFECT OF THE PROTOCOLS , THE QUESTION OF THE LEGALITY OF THE IMPOSITION OF THE DUTY FOR ADMINISTRATIVE SERVICES MUST , IN RESPECT OF THE PERIOD AFTER 1 JULY 1968 , BE CONSIDERED EXCLUSIVELY IN THE LIGHT OF THE COMMON CUSTOMS TARIFF . IN THAT REGARD IT SUFFICES TO REFER TO THE JUDGMENT OF 13 DECEMBER 1973 IN JOINED CASES 37 AND 38/73 , DIAMANTARBEIDERS V INDIAMEX , ( 1973 ) ECR 1609 , FROM WHICH IT FOLLOWS THAT THE MEMBER STATES ARE PROHIBITED , BY VIRTUE OF THE PROVISIONS OF THE TREATY ON THE CUSTOMS UNION ( ARTICLES 18 TO 29 ) AND ON THE COMMON COMMERCIAL POLICY ( ARTICLE 113 ), FROM ALTERING THE LEVEL OF THE CHARGE IMPOSED UNDER THE COMMON CUSTOMS TARIFF . THEREFORE A MEMBER STATE MAY NOT UNILATERALLY RAISE THE LEVEL OF THE COMMON CUSTOMS TARIFF BY THE IMPOSITION OF ADDITIONAL NATIONAL DUTIES OR CHARGES .
27 HOWEVER , AS IS CLEAR FROM THE SAME JUDGMENT , THE CHARGES WHICH WERE ALREADY IN EXISTENCE AT THE DATE OF THE ENTRY INTO FORCE OF THE COMMON CUSTOMS TARIFF COULD NOT , IN PARTICULAR ON GROUNDS OF LEGAL CERTAINTY , BE REGARDED AS INAPPLICABLE EXCEPT BY VIRTUE OF SPECIAL PROVISIONS ADOPTED BY THE COMMUNITY .
28 SINCE NO SUCH PROVISION HAS BEEN ADOPTED IN RELATION TO THE DISPUTED DUTY IN SO FAR AS IT APPLIES TO THE IMPORTATION OF GOODS FROM NON-MEMBER COUNTRIES , IT MUST BE CONCLUDED THAT THAT DUTY COULD LAWFULLY BE CHARGED DURING THE PERIOD FOLLOWING THE ENTRY INTO FORCE OF THE COMMON CUSTOMS TARIFF UNTIL THE REPEAL OF LAW NO 330 .
29 IN ORDER TO DETERMINE THE LEGAL POSITION PRIOR TO THE INTRODUCTION OF THE COMMON CUSTOMS TARIFF