a) The implicit amendment
An amendment is done implicitly when the States Parties conclude successive treaties relating to the same-subject-matter. Unless otherwise provided for in an agreement, the earlier treaty applies only to the extent its provisions are compatible with the later treaty (in conformity with the latin maxim
lex posterior derogat legi priori according to which the later treaty prevails over an earlier one if both regulate the same subject-matter, Article 30 (3)).
In view of the provisions concerning
e x p l i c i t amendments between certain parties only (Article 41) the implicit amendment must be considered as problematic, since it does not warrant the same transparency in the course of a negotiation:
In particular, parties which want to modify a treaty in accordance with Article 41, para. 2 have to notify the other parties of their intention. This provisions aims at ensuring that negotiations are conducted in
good faith with parties being aware of the relevant circumstances.
