More common and yet more troublesome legal issues of international liability for transboundary damage arise from normal industrial and technical activities, generally characterized as chronic transfrontier pollution via air, water, or land use. In contrast to the types of damage studied in Part I, the type of damage considered in this part is usually caused by deliberate, occasional, or cumulative acts with harmful effects. This type of damage is conveniently referred to as non-accidental damage.

Before embarking on an analysis of the substantive rules and principles of international liability, this chapter will begin with the factual background to non-accidental damage cases, which will be divided into three parts: air pollution, water damage, and damage from land use. For the most part, cases from the two major industrial regions – North America and Western Europe – will be chosen for examination.

Emanating primarily from the normal uses of natural resources shared among States, the matter of transboundary damage is in the final analysis about balancing interests between the relevant States. In such cases, the traditional doctrine of sovereignty has played a fundamental role in maintaining the normal order of State relations. The notion of shared resources, the doctrine of due diligence, and the concept of significant damage, all of which have evolved along with the doctrine, have been increasingly adopted in various legal instruments as guidelines for the contemporaneous use of natural resources by more than one State.