The same contract can imply obligations for a plurality of parties in the same position and, to be precise, the same concurrent position (contract is jointly concluded) instead of a consecutive position (such as that derived, for example, from assignment of rights or succession). This plurality of parties may be both of obligors (passive) and of obligees (active). A plurality of obligors and obligees is also possible at the same time. These are frequent hypotheses in international trade law (especially passive severability); that is why a specific regulation which takes into account particularities of each case seems convenient.

In case of plurality of obligors, it is possible that each one is obliged to perform only a part of the obligation, so that the obligee has only the right to claim against each obligor for its part. In such a case, the plural obligation is called “joint”, “separate” (Article 11.1.11 UP; Article 10:101 PECL) or “mancomunada simple” (in civil codes such as the Guatemalan, Honduran, Mexican, Panamanian and Puerto Rican). If obligees are jointly obliged, they have only the right to claim their parts of the credit and the obligor must perform only its separate part to each one. In both cases, division or fragmentation of the obligation or the rights implies the independent nature of each obligation, so that acts of modification or extinction of obligation are only referred to each obligor or obligee independently and have effect only in relation with each one. Each obligation and each right are different and independent to all intents and purposes. This kind of obligation calls for a non-mandatory regulation [Article 4.4.1 (2)], according to which each joint co-obligor is obliged for an equal share. This rule is found in several civil codes (Article 246.1 of the Cuban Civil Code; Article 1.348 of the Guatemalan Civil Code; Article 6:6.1º of the Dutch and Suriname Civil Code; Article 1.986 of the Mexican Civil Code; Article 1.929 of the Nicaraguan Civil Code; Article 1.024 of the Panamanian Civil Code; Article 1.091 of the Puerto Rican Civil Code), as well as in Article 10:103 of the PECL.

In commercial contracts, obligations assumed by a plurality of obligors are usually joint and several. In this case, co-obligors are obliged to perform a single obligation, which may be wholly claimed by the obligee from any obligor [Article 4.4.1 (1)]. This is the sense of the severability between obligors widespread in civil codes (Article 637 of the Costa Rican Civil Code; Article 1.568 of the Colombian Civil Code; Article 248 of the Cuban Civil Code; Article 1.200 of the Dominican and French Civil Code; Article 1.352 of the Guatemalan Civil Code; Article 987 of the Haitian Civil Code; Article 1.400 of the Honduran Civil Code; Article 6:6.1º of the Dutch and Suriname Civil Code; Article 1.987 of the Mexican Civil Code; Article 1.924 of the Nicaraguan Civil Code; Article 1.024 of the Panamanian Civil Code; Article 1.090 of the Puerto Rican Civil Code; Article 1.034 of the Saint-Lucian Civil Code; Article 1.221 of the of the Venezuelan Civil Code; Article 178 Proposals for the Reform of the French law on obligations of 2013), as well as in Article 11.1.1 UP; Article 10:101 (3) PECL; III-4:102 (3) DCFR. In common law systems and particularly in English law these obligations are called “joint and several”, while separate obligations are named simply as “joint” obligations.

If the co-obligor sued by the obligee performs more than its share, it has an action for recovery against the other obligors. Hence regulation of external relationships between co-obligors and obligee is necessary (Articles 4.4.2 to 4.4.7), as well as regulation of internal relationships between co-obligors themselves where one of them has performed wholly or in part (Articles 4.4.8 and 4.4.9).