On 25 January, the Greek Parliament ratified the Prespa agreement, ending three decades of conflict over the name between Athens and Skopje. The former Yugoslav Republic of Macedonia is now called the “Republic of Northern Macedonia” and its citizens are called “Macedonians/citizens of the Republic of Northern Macedonia.” The citizens of northern Macedonia speak the “Macedonian” language that belongs (as the agreement explains) to the family of southern Slavic languages. If the reference to erga omnes in the Prespa agreement does not concern an obligation imposed on all third parties to recognize the new official name of Northern Macedonia, one might assume that it refers to the famous diktat of the Barcelona Traction case, according to which obligations to the international community as a whole are the concern of all States and that all States “can therefore have a legal interest in their protection”.  This is what was done in Section 48 of the articles relating to state responsibility, which recognizes the obligation of all States to invoke the responsibility of a state for breaching an obligation due to the international community as a whole, and to request an end to unlawful conduct, assurances and guarantees of non-repetition, as well as reparation in the interests of the aggrieved state or beneficiaries of the leesiferous undertaking.  The issue of collective application has already been raised with respect to objective status/rules contracts in the ILC`s work on treaty law, in which the draft article 63, paragraph 3, point b), Waldock`s third report to the ILC stipulated that third countries “have the right to invoke the provisions of the general regime and to exercise a common law that they can grant.”  It is therefore clear that, under this prism, the Erga omnes no longer results in an obligation imposed on all third parties, but on a general interest granted to them “when a contractual scheme is imposed”.  In other words, it becomes an invitation to “participate in the collective affirmation of the values that characterize international public order.”  This is a transfer of the impact of contracts to third parties to its final recourse to liability for violations of these rules. But nothing in Prespa`s agreement starts from such a reading. Not only does Article 20, paragraph 7 limit the potential for third-party effects, but Article 19 on the Peaceful Settlement also does not mention the possibility for third countries to raise issues relating to compliance with the agreement. The same is true of Article 1, paragraph 13, in which only the parties can require corrections of errors and errors concerning the official name of the second part. Therefore, if there is an erga omnes obligation, it is an erga omnes partes one , which appears to be a bad name in the case of a bilateral treaty. In other words, only Greece can rely on the lack of diligence on the part of Northern Macedonia to ensure that third parties use the new official name.  And this duty of care is remarkably low, as it will manifest now.
The Prespa agreement is the short name of the contract, named after the place where it was signed, lake Prespa. Its full name is the final agreement on the settlement of initiatives, as described in UN Security Council Resolutions 817 (1993) and 845 (1993), the lifting of the 1995 interim agreement and the establishment of a strategic partnership between the parties. One of the fundamental rules of contract law is that agreements produce only multi-party effects, that is, between contracting parties; for third parties, a contract is a res inter alios acta.