++++ Common Customs Tariff - Exemption from import duties - Scientific instruments and apparatus - Commission decision - Power of appraisal subject to procedural guarantees for persons applying for an exemption - Review by the Court - Procedural guarantees not respected - Illegality (Regulation (EEC) No 1798/75 of the Council; Commission Regulation No 2784/79, Art. 7; Commission Decision 83/348)