1 By order of 1 February 1989, which was received at the Court on 6 March 1981, the Finanzgericht ( Finance Court ) Duesseldorf referred to the Court for a preliminary ruling pursuant to Article 177 of the EEC Treaty a question concerning the interpretation of various provisions of Council Regulation ( EEC ) No 857/84 of 31 March 1984 adopting general rules for the application of the levy referred to in Article 5c of Regulation ( EEC ) No 804/68 in the milk and milk products sector and Commission Regulation ( EEC ) No 1371/84 of 16 May 1984 laying down detailed rules for the application of the additional levy referred to in Article 5c of Regulation ( EEC ) No 804/68 ( Official Journal 1984, L 132, p . 11 ).
2 That question was raised in a dispute between Alfons Berkenheide, a farmer, and the Hauptzollamt ( Principal Customs Office ) Muenster in connection with the reference quantity allocated to him under the additional levy system for milk .
3 Mr Berkenheide delivered to the cooperative dairy Muensterland eG 114 306 kg of milk in 1980, 105 970 kg in 1981, 102 472 kg in 1982 and 121 721 kg in 1983 . On the basis of his deliveries in 1983, he was allocated a reference quantity of 110 900 kg . That figure represents the quantity of milk delivered by him in 1983, namely 121 721 kg, reduced by an abatement rate of 4%, and by a further abatement of 4.9% on the ground that in 1983 the plaintiff delivered a greater quantity of milk than in 1981 .
4 By Regulation No 856/84 of 31 March 1984 amending Regulation No 804/68 on the common organization of the market in milk and milk products ( Official Journal 1984, L 90, p . 10 ) the Council introduced an additional levy payable on the quantities of milk delivered in excess of a reference quantity to be determined : the levy is payable either by milk producers ( formula A ) or by purchasers of milk or other milk products, who pass it on to producers who have increased their deliveries in proportion to their contribution to the excess over the purchaser' s reference quantity ( formula B ).
5 The detailed rules for calculating the reference quantity, that is to say the quantities exempt from the additional levy, were laid down by Council Regulation No 857/84, referred to above . According to Article 2(1 ) of that regulation the reference quantity is to be equal to the quantity of milk or milk equivalent delivered or purchased during the 1981 calendar year, plus 1 %. However, Member States may provide, in accordance with Article 2(2 ), that on their territory the reference quantity is to be equal to the quantity of milk or milk equivalent delivered or purchased during the 1982 or 1983 calendar year, weighted by a percentage established so as not to exceed the guaranteed quantity for the Member State concerned . That percentage may be varied on the basis of, amongst other things, the level of deliveries by certain categories of persons liable to pay the levy between 1981 and 1983, under conditions to be determined according to the management committee procedure .
6 Derogations from those rules are provided for, in certain specified cases, by Articles 3, 4 and 4a of Regulation No 857/84 . More specifically, Article 3(3 ) of that regulation provides that "producers whose milk production during the reference year referred to under Article 2 has been affected by exceptional events occurring before or during that year shall obtain, on request, reference to another calendar reference year within the 1981 to 1983 period ".
7 The detailed rules for the application of the additional levy were laid down by Commission Regulation No 1371/84, referred to above . According to Article 2(1 ) of that regulation, Member States which make use of the option indicated in the second sentence of Article 2(2 ) of Regulation No 857/84 to vary the percentage applied to determine the reference quantities for producers and/or purchasers for the application of formula A and/or B are to take account of, amongst other factors, the trend between 1981 and 1983 in deliveries by certain categories of persons liable to pay the levy as defined in terms of that trend and, where appropriate, in relation to the average trend of deliveries in the Member State in question . Article 3 of that regulation contains a list of special situations justifying the use of a different reference calendar year under Article 3(3 ) of Regulation No 857/84 .
8 When implementing the Community rules concerning the additional levy on milk, the Federal Republic of Germany opted for the year 1983 under formula A ( the producer formula ). The reference quantity for producers established on German territory is, as a general rule, equal to the quantity of milk delivered by them during the 1983 calendar year, reduced by 4 %. That abatement rate is increased where the quantity of milk delivered during the 1983 calendar year is greater than that delivered during the 1981 calendar year, in accordance with a given formula, but not by more than five percentage points .
9 In an action brought before the Finanzgericht Duesseldorf, Mr Berkenheide claimed that his reference quantity should be recalculated without applying the increase in the abatement rate based on the increase in his production between 1981 and 1983 . In support of his claim he relies on the existence of an exceptional event within the meaning of Article 3(3 ) of Regulation No 857/84, namely the fact that milk production on his farm was diminished in 1981 and 1982 as a result of an outbreak of mastitis in his herd .
10 Taking the view that the solution of the dispute depended on the interpretation of provisions of Community law concerning the additional levy on milk, the Finanzgericht Duesseldorf stayed the proceedings and referred the following question to the Court for a preliminary ruling : "Is it contrary to Article 3(3 ) of Council Regulation ( EEC ) No 857/84 of 31 March 1984 ( Official Journal 1984, L 90, p . 13 ) in conjunction with Article 3 of Commission Regulation ( EEC ) No 1371/84 of 16 May 1984 ( Official Journal 1984, L 132, p . 11 ) to interpret the second sentence of Paragraph 4(2 ) of the Milch-Garantiemengen-Verordnung ( Milk ( Guaranteed Quantities ) Regulation ) of 25 May 1984 ( Bundesgesetzblatt 1984 I, p . 720 ), as amended for the first time by the regulation of 27 September 1984 ( Bundesgesetzblatt 1984 I, p . 1255 ), so as to mean that if milk production in the 1981 calendar year was affected by an exceptional event ( an epizootic ) within the meaning of the abovementioned provisions of Community law the quantity of milk which it is estimated that the milk producer would have produced in 1981 had the event not occurred, rather than the quantity actually produced in 1981, is taken as the basis for calculating the 'Steigerungsabzug' ( abatement based on the increase in production )?"
11 Reference is made to the Report for the Hearing for a fuller account of the facts of the case, the relevant provisions of Community and national law, the course of the procedure and the observations submitted to the Court, which are mentioned or discussed hereinafter only in so far as is necessary for the reasoning of the Court .
12 The question submitted for a preliminary ruling seeks in substance to ascertain whether the provisions of Council Regulation No 857/84 of 31 March 1984 and of Commission Regulation No 1371/84 of 16 May 1984 permit, in the case of a Member State which has chosen 1983 as the reference year, account to be taken of the situation of producers whose milk production was affected by an exceptional event in 1981 or 1982 .
13 In order to answer that question, it is necessary to begin by examining the scope of Article 3(3 ) of Regulation No 857/84 and Article 3 of Regulation No 1371/84, which are expressly referred to in the order for reference . Those provisions enable producers whose milk production has been appreciably affected by certain exceptional events during the calendar year adopted as the reference year by the Member State concerned to obtain reference to another calendar reference year within the period from 1981 to 1983 .
14 As the Court has held, most recently in its judgment of 27 June 1989 in Case 113/88 Leukhardt v Hauptzollamt Reutlingen (( 1989 )) ECR 1991, paragraph 13 ), the structure and purpose of the regulations on the additional levy indicate that they contain an exhaustive list of the situations in which reference quantities or individual quantities may be granted and set out precise rules concerning the determination of those quantities .
15 Since Article 3(3 ) of Regulation No 857/84 and Article 3 of Regulation No 1371/84 apply, as is clear from their wording, solely to a situation in which a farmer' s milk production has been appreciably affected by an exceptional event during the reference year adopted by the Member State in question, it follows that they do not apply to producers who, as in this case, were affected by an exceptional event during a year other than the reference year .
16 Although in its order for reference the national court refers only to the aforesaid provisions, it seems appropriate, in view of the documents before the Court and in order to provide the national court with all the elements of Community law which may assist it in resolving the dispute in the main proceedings, also to consider the scope of Article 2(2 ) of Regulation No 857/84 and Article 2(1 ) of Regulation No 1371/84 . Those provisions give Member States who choose the 1982 or 1983 calendar year as the reference year the option of varying the percentage weighting for the determination of reference quantities on the basis of, amongst other criteria, the trend between 1981 and 1983 in deliveries by certain categories of persons liable to pay the levy .
17 It is for the Member States, when they make use of that option, to determine the categories of persons liable to pay the levy to whom those variations are to be applied, provided those categories are defined in compliance with the aims pursued by the relevant Community legislation .
18 As the Court pointed out in its judgment of 25 November 1986 in Joined Cases 201 and 202/85 Klensch v Secrétaire d' État (( 1986 )) ECR 3477, paragraph 14, the option to vary the reference quantities in accordance with the categories of persons liable to pay the levy is designed to enable Member States which have adopted 1982 or 1983 as the reference year to take account of structural changes which took place after 1981 .
19 It follows that where, as in this case, a Member State decides to increase the abatement rate applied to the quantities of milk delivered by producers during the reference year on the basis of the increase in deliveries by those producers between 1981 and 1983, Community law does not preclude exemption in respect of that increase from being granted to the category of producers whose increase in deliveries during that period is not the result of a structural change or, in particular, account being taken of the situation of the category of producers whose milk production was affected by an exceptional event in 1981 or 1982 .
20 It is for the national court to assess whether and, if necessary, to what extent its national legal system enables it, in the absence of provisions of national law expressly laid down to that effect, to take into consideration a situation such as that of the plaintiff in the main proceedings .
21 For those reasons, the answer to the question submitted must be that the provisions of Article 3(3 ) of Council Regulation No 857/84 of 31 March 1984 in conjunction with Article 3 of Commission Regulation No 1371/84 of 16 May 1984 do not apply to the situation of producers who were affected by an exceptional event in a year other than the reference year . However, in the case of a Member State which has chosen 1983 as the reference year and has made use of the option of varying the percentage weighting for the determination of the reference quantities on the basis of the trend in deliveries by producers between 1981 and 1983, the provisions of Article 2(2 ) of Regulation No 857/84 in conjunction with Article 2(1 ) of Regulation No 1371/84 permit account to be taken for the purposes of such variation of the situation of the category of producers whose milk production was affected by an exceptional event in 1981 or 1982 .