Facts

• Petitioners Constante and Corazon Amor De Castro (two of the co-principals) were co-owners, with others, of four lots in Cubao, Quezon City. Constante, acting for himself and his co-owners, authorised private respondent Francisco Artigo (the agent/broker) in writing to act as real estate broker in the sale of the properties, for a 5% commission. (Because Constante signed for himself and for the rest, the appointment was one common undertaking rather than several separate ones — the fact that later makes all the co-owners solidarily liable to the broker.)
• Artigo found a prospective buyer, Times Transit Corporation (the third person), and brought the parties together.
• Negotiations led to the sale of two of the lots.
• Artigo received a partial payment on his commission, in the amount of ₱48,893.76, but claimed the balance of what was due him.
• He then discovered that the De Castros had sold two more lots to the same buyer, Times Transit, without paying him any commission on those sales. (The later sales were concluded by the owners directly, the broker having already brought that buyer to the table.)
• He sued to collect.
• The De Castros defended on several grounds: that Artigo's commission had already been fully paid; that his authority covered only the first transaction; and — procedurally — that the complaint should be dismissed for failure to implead the other co-owners as indispensable parties.
• Regional Trial Court — for Artigo. The Regional Trial Court ruled for Artigo.
• Court of Appeals — affirmed. The Court of Appeals affirmed.

Issue

1. Whether the other co-owners are indispensable parties whose non-joinder is fatal to the action.
2. Whether Artigo is entitled to a commission on the sale of the additional lots.

Ruling

1. No. The co-owners are solidary debtors, not indispensable parties; Artigo could sue any one of them for the entire obligation.
2. Yes. Artigo was the procuring cause of the sales to Times Transit and is entitled to his commission.

Ratio

• Article 1915§ provides:

If two or more persons have appointed an agent for a common transaction or undertaking, they shall be solidarily liable to the agent for all the consequences of the agency.

• The De Castros and their co-owners appointed Artigo for one common undertaking — the sale of the co-owned lots.
• The reason for the rule is the indivisibility of the agency: the agent renders one undivided service for all, and it would be unjust to require him to sue each principal for a proportionate share.
• Being solidary debtors§, each is liable for the whole obligation, and the creditor may proceed against any one of them (Art. 1216§).
• Solidary debtors are therefore not indispensable parties; the non-joinder of the others did not affect the court's power to render complete relief.

• A broker is entitled to his commission when he is the procuring cause of the sale — the "proximate cause," meaning the one who originated a series of events which, without break in their continuity, resulted in the accomplishment of the transaction.
• The test is whether the broker's efforts brought the buyer and seller together.
• Artigo did exactly that: he located Times Transit and set the negotiations in motion.
• That the parties afterwards concluded further sales directly, and that the later lots were sold in a separate transaction, does not defeat his right.
• The subsequent sales were the fruit of the relationship he created.

• The Court took note of the De Castros' conduct in concluding additional sales with the very buyer Artigo had produced, while withholding his commission.
• A principal may not reap the benefit of the agent's efforts and then cut him out of the compensation those efforts earned.

Doctrine

• Article 1915§. Two or more persons who appoint an agent for a common transaction are solidarily liable to him for all the consequences of the agency. The rule rests on the indivisibility of the agency.
• Solidary debtors are not indispensable parties. The agent may sue any one of them for the entire amount; failure to implead the rest is not a ground for dismissal.
• Procuring cause. A broker earns his commission by setting in motion the unbroken chain of events that produces the sale. Later transactions with the same buyer, concluded directly by the principal, do not extinguish that right.