1. How is overlapping jurisdiction between treaty bodies (e.g. the COP under the UNFCCC and another treaty body or international organization) addressed under international law where both bodies have authority over the same subject matter?

2. If there is no ‘exclusive authority’ of a treaty body or international organization, does international law set out rules as to what would happen where both the COP and the other treaty body or international organization created conflicting international regimes to raise finance.

Summary:

Overlapping jurisdiction between treaty regimes is best addressed proactively through express provision in the later treaty and/or through ‘synergy arrangements’ adopted by the Parties to all the regimes in question. The latter could be adopted as COP/institutional decisions.

In the absence of such specific provision (or in the event of a dispute), it is possible that the rules laid out in Article 30(4) Vienna Convention would apply. This means that in cases where the parties to the later treaty do not include all the parties to the earlier one (1) as between States Parties to both treaties, the earlier treaty applies only to the extent that its provisions are compatible with the later treaty; (2) as between a State party to both treaties and a State party to only one of the treaties, the treaty to which both States are parties governs their mutual rights and obligations. (Article 30(4)).

Advice:

The query refers to overlapping jurisdiction between treaty bodies such as the UNFCCC COP and other treaty bodies or international organisations. This situation could arise because the specific terms of the treaties establishing the bodies in question, or which those bodies administer, confer jurisdiction which overlaps, at least to a degree. The query does not seek specific advice on particular treaties however and this advice is therefore limited to an examination of the general rules which apply under the law of treaties.

By way of example, the International Maritime Organisation (IMO) is a United Nations specialized agency with responsibility for the safety and security of shipping and the prevention of marine pollution by ships and administers a number of conventions concerned with those issues. Issues of potential overlap with the climate change regime would have to be examined by reference to the particular treaty giving rise to the conflict.

There are essentially two ways of resolving overlap:

(1) express provisions in the later treaty; or

(2) in accordance with the rules set out in Article 30 of the Vienna Convention (if it applies).

It is not possible to give a view on whether Article 30 of the Vienna Convention (see below) would apply without a detailed examination of the terms of the specific treaties in question, including the rules adopted governing the powers of the respective bodies. The scope of application of Article 30 is not clear, but where there is a conflict between regimes in a matter as specific as the taxation of bunker fuel, the application of Article 30 of the Vienna Convention should not be ruled out.

Express provision addressing overlapping jurisdiction

Although there are specific rules governing the application of successive treaties to the same subject matter, which may indeed be relevant to the UNFCCC regime (now or in the future), it is important to note that potential conflict between different international regimes can be removed or minimised through the adoption of express provision in the later treaty and/or by adopting a memorandum of understanding between the parties to potentially conflicting regimes. This should be the preferred way of addressing the situation if possible as it reduces the possibility of disputes arising at a later stage.

There are many examples of this type of provision and practice. The ‘synergies’ model used in the waste/chemicals sector is of interest although it is not clear that this model would be appropriate where there were fundamental differences in approach between the regimes (or where key parties were not party to all the relevant regimes).

Application of Article 30 of the Vienna Convention

Where overlapping jurisdiction is not expressly addressed, Article 30 of the Vienna Convention 1969  may apply. Article 30 addresses the situation where successive treaties ‘relate to the same subject matter’ and sets out a series of rules determining which provisions apply as between which parties .

The first question therefore is whether the treaties in question ‘apply to the same subject matter’. Leading commentators have pointed out that the meaning of this phrase is ‘not clear’ and expressed the view that Article 30 does not apply where a general treaty ‘impinges indirectly on the content of a particular provision of an earlier treaty’ .

In the absence of detailed consideration of the regimes in question it is not possible to express a view on whether the relevant treaties of concern here ‘apply to the same subject matter’. However where, for example, a UNFCCC climate financing regime establishes a levy which arguably conflicts with a levy regime operated under another treaty dealing with a particular sector, Article 30 may be applicable. Further detailed advice should be sought as necessary by reference to the precise terms of the various regimes in question.

If Article 30 were to apply, the rules concerning overlapping jurisidiction can be summarised as follows:

• When a treaty specifies that it is subject to, or is not to be considered as incompatible with, an earlier or later treaty, the provisions of that other treaty prevail (Article 30(2));
• When all the parties to the earlier treaty are parties also to the later treaty but the earlier treaty is not terminated or suspended…the earlier treaty applies only to the extent that its provisions are compatible with those of the later treaty (Article 30(3));
• When the parties to the later treaty do not include all the parties to the earlier one :
  • as between States Parties to both treaties the same rule applies as in Article 30(3) [i.e. the earlier treaty applies only to the extent that its provisions are compatible with the later treaty; (Article 30(4)(a))
  • as between a State party to both treaties and a State party to only one of the treaties, the treaty to which both States are parties governs their mutual rights and obligations. (Article 30(4)(b))

Whether or not Article 30 does apply, it is clear that inserting express provision into the treaty in question/adopting specific ‘synergy arrangements’ is likely to be the best way or reducing ambiguity and indicating whether a particular regime takes precedence over another. On the other hand, under the rules laid down in Article 30(3) and (4), silence in the later treaty may have the effect of allowing the later treaty to supersede the earlier (in relation to parties to both where the provisions of the two treaties are incompatible). If Article 30 is applicable, it is likely that not all states will be party to two (or more) multilateral agreements and therefore, in the absence of express provision (para 2), para 4 will apply which means that different rules will apply as between different parties depending on which treaty both states are party to. Article 30(4)(b) derives from the general principle that parties to a treaty should refrain from acts inconsistent with their treaty obligations and this includes the duty not to conclude with third states treaties inconsistent with their obligations under their existing treaties.