Short answer. Yes, generally. Article 1183 of the Civil Code states that conditions contrary to law, good customs, or public policy annul the obligation that depends on them. The entire obligation tied to such a condition becomes void — not just the condition itself. An exception applies only if the obligation is divisible.
What the law says
Impossible conditions, those contrary to good customs or public policy and those prohibited by law shall annul the obligation which depends upon them.
Civil Code, Article 1183 — Impossible and Unlawful Conditions. Read the full provision →
The rule: illegal condition, void obligation
Article 1183 groups together three types of problematic conditions: those that are physically impossible, those contrary to good customs or public policy, and those prohibited by law. When an obligation depends on any of these, the article is clear: the obligation is annulled. The condition does not simply fall away while leaving the obligation standing — the entire arrangement that hinges on it is extinguished. If someone agreed to pay you only if you bribed an official, or committed fraud, or violated a statute, the whole promise is legally void.
Why the obligation — not just the condition — is affected
This matters because the outcome under Article 1183 is different from what happens with some other defective conditions. Here, the unlawful condition is not simply ignored or treated as unwritten — it takes the obligation down with it. The reasoning is that the law cannot enforce an arrangement whose triggering event is itself illegal. Allowing the obligation to survive without the condition would change the terms the parties actually agreed to; nullifying both preserves the integrity of the legal system.
The divisibility exception
There is one important qualification. Article 1183 provides that if the obligation is divisible, the part not affected by the impossible or unlawful condition remains valid. For example, if a contract has two independent components — one conditioned on something illegal, one conditioned on something perfectly lawful — the lawful portion survives. Whether an obligation is divisible depends on whether its parts can be separated and enforced independently without defeating the overall purpose of the agreement. Courts look at the substance of what the parties intended, not just how the contract is structured on paper.
What this means if you are the one bound
If you signed something that requires you to perform an illegal act as a condition, the safest reading of Article 1183 is that you are not legally bound to fulfill either the condition or the corresponding obligation. However, the other party may contest this, particularly if the illegality was in a side condition and the rest of the agreement is separable. Do not simply refuse performance without legal advice — you need to assess whether the arrangement is truly void, whether restitution is owed for anything already exchanged, and whether any other provision of the Civil Code applies to your specific situation.
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.
- Heirs of Severina San Miguel, et al. vs. The Hon. Court of Appeals, G.R. No. 136054, September 5, 2001 — read the decision on LawPhil →