Short answer. The supplier, unless your contract gives the choice to you. Article 1200 provides that the right of choice belongs to the debtor unless it has been expressly granted to the creditor — and the debtor may not choose a prestation that is impossible, unlawful, or could not have been the object of the obligation.
What the law says
The right of choice belongs to the debtor, unless it has been expressly granted to the creditor. The debtor shall have no right to choose those prestations which are impossible, unlawful or which could not have been the object of the obligation.
Civil Code, Article 1200 — Alternative Obligations; Right of Choice. Read the full provision →
The default belongs to the debtor
Article 1200 provides: The right of choice belongs to the debtor, unless it has been expressly granted to the creditor. The debtor shall have no right to choose those prestations which are impossible, unlawful or which could not have been the object of the obligation. Note the word expressly. A buyer who assumed he would pick, because he is the one paying, has assumed wrong unless the contract says so. Where you want the choice, the clause has to give it to you in terms — silence hands it to the supplier.
The choice is not unlimited
The second sentence is the buyer's protection. A supplier cannot satisfy the contract by selecting something impossible or unlawful, and cannot pick an option that was never really within the agreement. Two further articles narrow him. Article 1202 makes him lose the right of choice when only one of the prestations remains practicable — he must then deliver that one. And Article 1244 stops him substituting outside the list altogether: a debtor cannot compel the creditor to receive a different thing, even one of the same or greater value. Product C is not an answer when the contract said A or B.
The choice has to reach you
A choice made privately changes nothing. Article 1201 provides that the choice shall produce no effect except from the time it has been communicated. Until the supplier tells you which product he is delivering, the obligation stays alternative, and the consequences of that matter: which item's loss excuses him, what you may plan around, and when the obligation becomes a simple one to deliver a determinate thing. So insist on the election in writing, and treat an ambiguous shipping notice as no election at all.
If the choice is yours, protect it
Where the contract does give you the choice, two provisions matter. Article 1205 says the obligation ceases to be alternative from the day your selection is communicated to the debtor, so make the selection formally and keep proof of sending. Article 1203 covers obstruction from the other direction: if through the creditor's acts the debtor cannot make a choice according to the terms of the obligation, the debtor may rescind with damages — a reminder that a buyer who stalls, refuses to specify or keeps changing the requirement is not merely being difficult; he is putting the contract at risk.
Related provisions
- Civil Code, Article 1200 — Alternative Obligations; Right of Choice
- Civil Code, Article 1201 — Communication of the Choice
- Civil Code, Article 1202 — When Only One Prestation Is Practicable
- Civil Code, Article 1203 — Creditor's Acts Preventing Choice
- Civil Code, Article 1205 — Loss When the Creditor Has the Choice