Short answer. The party who was performing the obligation. Article 1170 makes anyone guilty of fraud, negligence or delay in performing an obligation liable for damages, and adds a fourth and much wider ground: contravening the tenor of the obligation, meaning performing it in any manner the agreement did not allow.

What the law says

Those who in the performance of their obligations are guilty of fraud, negligence, or delay, and those who in any manner contravene the tenor thereof, are liable for damages.

Civil Code, Article 1170 — Liability for Fraud, Negligence, Delay. Read the full provision →

One sentence, four ways to be liable

Article 1170 of the Civil Code is a single line: Those who in the performance of their obligations are guilty of fraud, negligence, or delay, and those who in any manner contravene the tenor thereof, are liable for damages. That is four separate grounds, not one. A party may be liable because he cheated, because he was careless, because he was late after demand, or simply because what he delivered was not what the obligation called for. They are alternatives, so a claimant does not have to prove bad faith to recover — establishing that performance departed from what was promised is often enough on its own.

Fraud and negligence are not the same claim

Fraud here is deliberate — a conscious, voluntary failure to perform, or performance designed to evade what was agreed. Negligence is the absence of the care the obligation required, without any intention to harm. The distinction is not academic. Article 1171 provides that responsibility arising from fraud is demandable in all obligations, and that a waiver of an action for future fraud is void, so a clause excusing a party in advance for his own deliberate breach does not hold. Liability for negligence, by contrast, may be regulated by the courts according to the circumstances, and the standard of care itself depends on what the obligation was.

"Contravene the tenor thereof" is the widest ground

The final clause — those who in any manner contravene the tenor thereof — catches breaches that are neither dishonest, careless nor late. Delivery of a different grade of material, work completed to a specification nobody agreed, a service rendered in a way the contract excluded: none of these need fault at all. The obligation said one thing and the party did another, and that alone founds liability. In most contract disputes this is the strongest ground available, and it is the one claimants most often overlook while trying to prove that the other side acted in bad faith.

Liability is one question, the amount is another

Article 1170 establishes who answers; it does not fix what they pay. Damages still have to be proved, and the loss claimed has to be connected to the breach rather than merely follow it in time. Before consulting anyone about a claim, gather the documents that show two things: exactly what performance was owed, and exactly what was delivered instead. The gap between those two is the case. Receipts, correspondence, specifications and the dates of every demand carry far more weight than a general account of how badly the other party behaved.

Cases citing this provision

These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.

Related provisions

Note. Statute text quoted on this page is reproduced from the official enactment and is linked to the full provision. The explanation around it is general legal information from Vivas & Nobles Law Office, not legal advice. Whether it applies to your situation depends on facts only a lawyer reviewing them can assess.