1. The appeal court finds that in principle the claimant has a claim to compensation under §§ 823 (2), 1004 of the BGB. It considers that the defendant had an obligation to keep the pest outbreak on his land within limits by the employment of chemical or mechanical means in accordance with the common practice. This was because the vine growers of a region formed a community of danger (Gefahrengemeinschaft) in which, on the one hand, they had contributed to an increased danger of the fungus attack by creating a monoculture and, on the other hand, their existence was threatened by the effect of the danger. As the defendant had not taken any measures to stop the outbreak of mildew on his land, he could be accused of an omission in breach of duty, which gave rise to liability.
II. These observations do not stand up to legal examination under the appeal in law.
1. The appeal court is correct in assuming at the outset that the defendant could only be obliged to provide compensation if his failure to protect his vines against the mildew attack by chemical or mechanical means was a breach of duty. If the claim was based on § 823 (1) of the BGB, a duty to act could arise from a duty of care owed to the public in general (Verkehrssicherungspflicht). If liability were linked to § 823 (2) in combination with § 1004 of the BGB, the defendant would have to be a "disturber" in the sense of § 1004 (1) of the BGB. That again presupposes that the invasion of property can be traced, at least indirectly, to the defendant's intention (reference omitted). This can only be accepted in respect of an omission if there is a duty to act. Here also it is therefore a question of whether the defendant had a corresponding duty of care owed to the public in general (reference omitted).
2. The appeal in law successfully contests the appeal court's view that the defendant was obliged to protect his vineyard against mildew attack.
a) The appeal court's idea that a "community of danger" existing between the vine growers obliged individuals to take measures to combat pests is not sustainable. The concept of a community of danger is not a legal institution generally recognised by statute law from which duties to act and to refrain from acting can be derived. The concept of the community of danger describes the situation where several persons are exposed to a risk affecting them alone. Such a situation can cause the legislator to make rules for the possible occurrence of the risk. But the form which these rules take is not prescribed beforehand: it is in the legislator's discretion. He can confine himself to allocating uniformly the disadvantages arising from realisation of the danger (e.g. [reference omitted]). He can also lay down duties. The subordinate legislator of Rheinland-Pfalz in 1997 created such a possibility in 1997 in the Land Regulation for the Protection of Planted Vineyards from Harmful Organisms (reference omitted). But so long as the legislator has not taken action, no duties to act arise from the membership of a special community of danger alone.
b) Contrary to the view of the reply to the appeal in law, it is not possible to conclude there is a duty of care to the public in general creating an obligation to take action simply from the agricultural use of land for vine-growing. It is admittedly recognised that a person who creates a source of danger is under such a duty of care. He must take the necessary precautions for the protection of business in order to prevent harm to third parties on realisation of the danger. But no generally valid concepts can be prescribed for when a type of conduct giving rise to duties of this kind has to be assumed: each case must be evaluated. Accordingly maintaining a vineyard cannot be regarded as the creation of a source of danger.
The Senate's case law indicates that the definition in § 1004 of the BGB is not fulfilled if the harm proceeding from land can be traced exclusively to the powers of nature (references omitted). That also prevents the user in such cases having special duties of care to the public in general imposed upon him. The appeal court has admittedly established that the agricultural use of land for vine growing, and the accompanying monoculture, favours the spread of plant pests like mildew. The fungus attack is not therefore just an accidental natural event, largely independent of human influence. At the same time, it is doubtful whether this justifies any different assessment of the matter. This is because the manager of a vineyard has not created a source of danger from which harmful effects spread to other land unilaterally. He merely takes part in an agricultural use which is generally prevalent and which only when combined with other such uses creates a source of danger by which all users are affected.
In any case, the fact that the cultivation of fields and meadowlands within the scope of normal agricultural use does not give rise to defensive claims under § 1004 of the BGB, even if disadvantageous effects spread as a result to neighbouring land (references omitted), is inconsistent with the assumption of a duty of care to the public in general. The neighbour must accept such repercussions and cannot expect the proprietor of the land from which these consequences emanate to take measures for the neighbour's protection. The establishment of such duties would set limits to agricultural use which would be too narrow. Agriculture can bring with it many kinds of disadvantages for neighbouring land, including (and especially) when cultivated land is used intensively and in large areas; and in particular for land which is part of an overall cultivation. Thus the type of cultivation can affect water drainage to the disadvantage of surrounding land (reference omitted). The type and extent of fertiliser use or vermin control can have an effect on ground water and surface water on neighbouring land (reference omitted). Or the maintenance of monocultures, as here, (but not confined to vine-growing) can increase the risk of a pest attack. Whether and to what extent it is necessary to intervene in a regulatory way in such cases must in principle remain the preserve of the legislator (or subordinate legislator). The fact that establishing duties to act of the kind that the claimant demands is not in any way compulsory is demonstrated in this very case. The subordinate legislator has not for instance considered it to be appropriate to impose on vineyard managers generally the duty of pest control. He has instead considered intervention for the protection of neighbouring vineyards from the spread of pests only to be required when proper cultivation has not taken place for two consecutive calendar years.
In this case the defendant's behaviour is within the limits of normal agricultural use. Temporary non-cultivation of an area of arable land does not generally represent a use extraneous to agriculture. It can be the consequence of an entrepreneurial decision which is sensible by agricultural standards. Such a type of cultivation would not generate any special duties for the protection of third parties from its harmful effects. That is the position here. The defendant refrained from cultivating the areas in 1995 in order to be able to obtain higher yields from other areas without exceeding his maximum quota. Such measures must be possible without extensive and, in particular, costly duties attaching to them.
c) Nor did the defendant have any duty to act from the angle of neighbouring community relationships linked with § 242 of the BGB. As a rule the concept of good faith (Treu und Glauben) within the scope of neighbouring community relationships does not create any independent claims; it takes effect as a barrier to the exercise of rights (references omitted). The Senate only regards it as necessary in exceptional cases to base a claim directly on the special relationship of neighbours i.e. when this is required on compelling grounds for a fair adjustment of interests (reference omitted). Nothing else will suffice for the assumption of a special duty to act. Such compelling grounds are not evident here. The subordinate legislator has also not proceeded on this basis, as has been explained.
d) Finally it cannot be assumed that the defendant had a duty in customary law to treat his vines with pest control agents to protect neighbouring land. Contrary to the view of the reply to the appeal in law, the claimant has not presented a sufficient argument for the existence of any such principle recognised in customary law...
3. Nor can the concept of maintenance of an installation threatening danger provide any assistance for the success of the claim (§ 907 (1) of the BGB): §§ 823 (2), 907 of the BGB. Apart from the fact that there is no finding that it was "foreseeable with certainty" that the defendant's vineyard would have the effects established in this case on the claimant's land - and such findings could hardly be made - the vineyard does not represent an installation anyway in the sense of the norm; it falls within the privilege contained in para 2 (reference omitted).
4. On the other hand, it is worth considering possible liability on the part of the defendant for violation of a duty to provide information. The Senate has already stated in the wool lice case (reference omitted) that in the case of a pest attack which the proprietor is not obliged to prevent, the neighbour can be granted the right, having regard to neighbouring community relationships, to take control measures on the land from which the interference originates. This must be considered in any case when - as here - the proprietor of the land where the interference originates will suffer no unreasonable harm from the control measures. Such action taken for one's own protection assumes, though, that the neighbour is informed in good time about the attack or threatened attack by the proprietor of the land on which the control is necessary. The proprietor can be obliged to do this under § 242 of the BGB, having regard to the neighbour relationship. If he does not fulfil this obligation, he can be obliged to pay compensation according to the principles of positive violation of a claim (positive Forderungsverletzung).
But a duty to provide information only exists if the neighbour needs information about the threatened danger. If he knows about the circumstances from which the danger arises, or if he should easily be able to recognise them, the principle of good faith does not require the other party to point this out to him again. That is the situation here. According to the evidence, and in particular the statements of the witness K, it could be recognised at the latest in June 1995, and in fact before an attack of mildew was evident, that the defendant was not cultivating the area next to the claimant's vineyard. It was therefore obvious to the claimant that the defendant was doing nothing to protect from pest attack on his vineyards. The Senate can use the result of this evidence because the stated facts are undisputed between the parties, as the observations in the appeal in law and the reply to the appeal in law show.