Page - 186 - in Loss and Damage from Climate Change - Concepts, Methods and Policy Options

186 F.SimlingerandB.Mayer laware constitutedby thegeneral practice of states accepted as law (Statute of the InternationalCourtofJustice,art.38(1)(b)).Atreatyisinsteadanagreementthrough which twoor several states voluntarily commit to complywith certain obligations. Whenastatefails torespect its internationalobligations, includingobligationsstem- ming from customary international law and treaty law, this state has a secondary obligation to cease thewrongful act andperform its international obligation and to make adequate reparation to any state injured (ILCArticles on Responsibility of States for InternationallyWrongfulActs, arts. 29–31). Section7.4.1examineswhetherexcessivegreenhousegasemissionscouldconsti- tuteabreachofanormofcustomaryinternational law—theno-harmprinciple—and consequentlyentailsanobligationtomakereparationfortheinjurycausedtotheter- ritoryofotherstates.Section7.4.2turnstothetreaty-basedinternationalclimatelaw regime.Thus,weelude, for thesakeofbrevity, anydiscussionofother treaty-based regimes, such as the provisions on pollution of themarine environment contained in theUNConventionon theLawof theSeasor theworkof the InternationalLaw Commissionon theprotectionof theatmosphere. 7.4.1 TheObligationofStatesNot toCauseSerious EnvironmentalHarm Thecontemporary international legal systemisbasedontheprinciple that statesare equal sovereigns. States could not be equal sovereigns if it was permitted for one state to interferewith the internal affairs of another state in anymanner thatwould seriouslyaffect the latter.Likewise, stateswouldnotbegenuinelyequal sovereigns if one statewas permitted to render the territory of another state uninhabitable or otherwise to significantly affect the conditions under which that territory can be used, for instance throughcausingseriousenvironmentalharmsacross international borders (seeOrderof13December2013 in the joinedproceedingsConstructionof aRoad inCostaRicaalong theSanJuanRiver (Nicaraguav.CostaRica);Certain ActivitiesCarriedOutbyNicaragua in theBorderArea (CostaRicav.Nicaragua), ProvisionalMeasures ICJRep2013,398). Theno-harmprinciple,asacorollaryoftheprincipleofequalsovereignty,wasfirst recognised in the1941arbitral award in theTrailSmelter case.Thiscaseconcerned a dispute betweenCanada and theUnited States over air pollution arising from a smelter inCanada,whichwasbrought bydominantwinds towards theUSState of Washington, causing serious environmental damages. In an oft-cited passage, the tribunaldeclared that: under theprinciplesof international law[…]nostatehas the right touseorpermit theuse of its territory in suchamanner as tocause injuryby fumes inor to the territoryof another or thepropertiesofpersons therein,whenthecase isofseriousconsequencesandthe injury is establishedbyclear andconvincingevidence (Trail SmelterArbitration: 1905).