Air does not respect any borders, travelling from one place to the other making transboundary air pollution a global crisis. The concept of transboundary air pollution spreads across the international boundaries causing massive issues, but in some countries, it is more harmful than others. Amidst all the global issues, international law experts have raised the dilemma of such pollution seeking stricter guidelines.^[i] Transboundary harm by definition means “harm caused in the territory of or in other places under the jurisdiction or control of a State other than the State of origin, whether or not the States concerned share a common border.” This can clearly be explained by the case of Trail Smelter, where it was stated that no state can utilize their resources in a way that will affect other countries.^[ii] The Trail Smelter arbitral tribunal stated in the dicta that under the principles of international law: “No State has the right to use or permit the use of its territory in such a manner as to cause injury by fumes in or to the territory of another or the properties or person therein, when the case is of serious consequence and the injury is established by clear and convincing evidence.”^[iii] This sic utere tuo concept has become the core rule of international transboundary pollution and is often known (not entirely accurately) as the “Trail Smelter rule” or “Trail Smelter principle“.^[iv]

The convention on Biological Diversity, which has a binding obligation and the ILC Draft Articles on Prevention of Transboundary Harm from Hazardous Activities 2001, which cannot be ignored, both strictly adhere to the concept of transboundary air pollution.^[v] The conventions present huge importance to the biological diversity and the usage of biological resources and technology to preserve the environment. In the interpretation and analysis of the term “Transboundary Harm”, there are four main essentials to be regarded as a problem to other countries, which include  (a) the activity conducted and the damage caused to the other country, (b) the distance between the country (c) whether the acts are caused by humans and (d) a certain level of threshold which calls for a legal action.^[vi]

International issues related to transboundary harm

Transboundary problems are often divided into two categories: substantive and procedural. To begin with the procedural concerns, principles of international environmental law have evolved in the setting of two basic aims that pull in opposite directions: nations have sovereign rights over their natural resources, and governments must not harm the environment.^[vii] The international world is constantly seeing a conflict between absolute territorial sovereignty and limited sovereignty. Outright territorial sovereignty, as the name implies, is the theory that a riparian state has complete authority over all resources in its territory and may utilize them without regard for the consequences to downstream or co-riparian states.^[viii] The Biodiversity Convention includes many murky regions, as is inevitable in this arrangement system, with expanding aims of particularly broad scope, arising from highly cantankerous dealings amid mesmerized groups. Furthermore, substantive concerns raise issues for the international body.^[ix]Substantive concerns often refer to actual environmental damage or harm committed across national borders, and include concepts such as the need to prevent major harm, the sustainable use of shared resources, and the equitable use of common natural assets. These concerns are critical to the understanding of the nature and scope of state duties under international law. Furthermore, the section under ‘International Issues Related to Transboundary Harm’ is quite brief and might benefit from a more in-depth analysis of these substantive ideas, as well as pertinent instances or case studies. A more thorough approach would improve the overall study and provide readers a better grasp of the complexity of resolving transboundary environmental degradation. Both its preambular presentations and substantive pieces are delivered in broad words, which are frequently hampered by such additional limitations. ^[x]These include phrases like ‘as appropriate’, ‘as far as possible’, ‘practicable in accordance with particular conditions and capabilities’, ‘taking into account special needs’, ‘likely to’, ‘grave and imminent’, ‘significant’, and such limited requirements as ‘endeavour’, ‘encourage’, ‘promote’, and ‘minimize’.^[xi] So far, it can be safely concluded that there are no substantive rules specific to the transboundary harm, except the ILC Draft Articles, which too have no binding force, thereby making it a part of those “soft law” conventions that are hardly referred back once signed.^[xii] However, if we scratch the surface of the ILC Articles, it seems an ideal framework for transboundary law, which not only defines the harm within a decent scope but also provides decent remedial measures after such harm has occurred.^[xiii] Moreover, invocation of state responsibility has also been provided in the same draft, making it exhaustive enough to cover all foreseeable situations. ^[xiv]

Should States face stringent global risk for transboundary damage under international law?

In the light of the above discussion, it is evident that transboundary air pollution poses a significant and growing challenge to international environmental governance. Despite various international efforts and legal instruments such as the Convention on Biological Diversity and the ILC Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, there remains a glaring gap in the existence of binding substantive rules that effectively address transboundary harm. The analysis shows that while procedural safeguards have seen some development, substantive obligations remain largely non-binding, framed in broad and often ambiguous language that dilutes their enforceability.

The concept of sic utere tuo ut alienum non laedas, as crystallized in the Trail Smelter case, remains a foundational principle, yet its application has not evolved into a universally binding norm capable of offering comprehensive protection against transboundary environmental harm. The recurring reliance on soft law instruments, filled with qualifiers such as “as appropriate,” “to the extent possible,” and “endeavor,” highlights the reluctance of the international community to impose firm obligations on states, thus weakening the global response to cross-border environmental threats.

The express conclusion that can be drawn is that, while significant frameworks and principles have been established, there is still no concrete, binding international regime specifically tailored to address transboundary harm in a comprehensive manner. The ILC Draft Articles, although ideal in theory and broad in scope, suffer from their non-binding nature, limiting their practical effectiveness. To truly address the global crisis of transboundary pollution, there is an urgent need for the international community to move beyond aspirational language and toward the creation of binding legal obligations that hold states accountable for cross-border environmental damage.

Until then, transboundary harm will continue to be governed more by fragmented principles and voluntary cooperation than by a cohesive legal framework, thereby impeding the achievement of meaningful environmental protection at the international level.

Endnotes

[i] Patricia Birnie, Alan Boyle, and Catherine Redgwell, International Law and the Environment (3rd edn, OUP 2009)

[ii] Owen McIntyre, ‘The Emergence of the “Duty to Cooperate” in International Environmental Law’ (2010) 21 YIEL 157

[iii] Trail Smelter Arbitration (United States v Canada) (1938 and 1941) 3 RIAA 1905

[iv] UN General Assembly, Declaration on the Human Environment (16 June 1972) UN Doc A/CONF.48/14/Rev.1 (Stockholm Declaration)

[v] Ibid.

[vi] Owen McIntyre, Environmental Protection of International Watercourses under International Law (Ashgate 2007)

[vii] Ibid.

[viii] Philippe Sands and Jacqueline Peel, Principles of International Environmental Law (4th edn, CUP 2018)

[ix] International Law Commission, Draft Principles on the Allocation of Loss in the Case of Transboundary Harm Arising Out of Hazardous Activities (2006) UN Doc A/61/10

[x] Ibid.

[xi] Edith Brown Weiss, ‘Environmental Equity: The Imperative for the Twenty-First Century’ (1992) 8 IJGLS 1

[xii] Xue Hanqin, ‘Transboundary Damage in International Law’ (2003) 42 Columbia J Trans L 85

[xiii] Alan Boyle, ‘State Responsibility and International Liability for Injurious Consequences of Acts Not Prohibited by International Law: A Necessary Distinction?’ (1990) 39(1) ICLQ 1

[xiv] Alan Boyle, ‘Transboundary Environmental Interference and the Origin of State Liability’ (1985) 53 BYIL 293