Short answer. The old law generally governs. Article 2253 provides that rights originating from acts done under the Civil Code of 1889 and other previous laws are governed by that old law, even if the new Code regulates them differently or does not recognize them, subject to a narrow exception for newly declared rights.
What the law says
The Civil Code of 1889 and other previous laws shall govern rights originating, under said laws, from acts done or events which took place under their regime, even though this Code may regulate them in a different manner, or may not recognize them.
Civil Code, Article 2253 — Old Law Governs Prior Acts. Read the full provision →
The old law controls rights that already originated under it
Article 2253 states the general transitional rule directly: the Civil Code of 1889 and other previous laws shall govern rights originating, under said laws, from acts done or events which took place under their regime, even though this Code may regulate them in a different manner, or may not recognize them. Because your contract was entered into before the new Code took effect, the rights and obligations that originated from that contract are, as a rule, governed by the old law under which the contract was made, not by whatever different treatment the new Code might give to similar contracts going forward.
Why the new Code does not simply override what already happened
This rule protects the stability of transactions and expectations that were formed while the old law was in effect. If the new Code automatically reached back and reinterpreted rights that had already originated under the previous regime, parties who structured their agreements around the law as it existed at the time would find the legal consequences of their own contracts changed retroactively. Article 2253 avoids that by anchoring the governing law to when the act or event that created the right actually took place.
The narrow exception for brand-new rights
The article is not a blanket rule locking every old transaction permanently into the old Code; it applies specifically to rights that already originated under the previous law. A separate rule in the same article addresses a right declared for the first time by the new Code, which can take effect immediately even for acts done earlier, but only to the extent it does not prejudice or impair a vested or acquired right of the same origin. This distinction matters if your contract also touches on matters the new Code treats in genuinely new ways.
What this means for your contract
Since your contract and the rights it created originated before the new Civil Code took effect, you should generally look to the Civil Code of 1889 and other previous laws to determine how those specific rights and obligations are governed, rather than assuming the current Code's provisions automatically apply retroactively to reshape what your contract already established at the time it was made.