In a preliminary ruling referred to the ECJ by the Tribunale amministrativo regionale del Lazio (Italy), the Court ruled on the validity of Commission Directive 2006/134/EC amending Council Directive 91/414/EEC concerning the placing of plant protection products on the market to include fenarimol as an active substance. A plant protection product must be listed as an active substance in Annex I of Directive 91/414 and satisfy the conditions set out therein before placement on the market can be authorized by the Member States. The Commission Directive established restrictions on the use of fenarimol during the time that it was included in Annex I. The complainant argued that the severity of the restrictions were not justified by the scientific studies carried out during the assessment procedure. The referring court added that the scientific assessment had resulted in positive conclusions and that the Commission had initially proposed to include the substance in Annex I without restrictions. The Court found that the restriction on the use of fenarimol was valid and in accordance with the principle of legal certainty, the precautionary principle and the principle of proportionality. The Court gave weight in its decision to remaining scientific uncertainty regarding potential endocrine disrupting properties of fenarimol.