1) The question in Philippine terms

In the Philippines, a “marriage settlement” (commonly called a prenuptial agreement or “prenup”) is not just an ordinary contract. It is a family-law instrument that fixes the property regime of the spouses (and related financial arrangements) and operates within mandatory rules of the Family Code, constitutional restrictions, and Philippine conflict-of-laws principles.

So the real issue is not simply “May we choose foreign law?” but:

Will Philippine law recognize a choice-of-law clause at all?
If recognized, to what extent will foreign law be applied—especially when one spouse is Filipino, the marriage is celebrated in the Philippines, or property is located in the Philippines?
What Philippine mandatory rules cannot be contracted around, even with a foreign-law clause?

The short Philippine-conflicts answer is: party autonomy exists, but it is narrower in marriage settlements than in commercial contracts, and it is sharply limited by public policy, mandatory Family Code rules, and property-in-the-Philippines rules (including constitutional limits on land ownership).

2) What a marriage settlement is under Philippine law

A. Core function: choosing the matrimonial property regime

For marriages governed by the Family Code framework, spouses may generally choose among property regimes (or craft a permitted mix), such as:

Absolute Community of Property (often the default when there is no valid settlement),
Conjugal Partnership of Gains (more common in older frameworks; still relevant in some contexts),
Complete Separation of Property, and
Other arrangements allowed by law, as long as they do not violate mandatory rules.

B. Timing and form matter more than in ordinary contracts

As a rule in Philippine family law, a marriage settlement that is intended to govern the marriage’s property relations must be:

Executed before the marriage (a “prenup” in the strict sense),
In writing and properly executed,
Often registered/recorded in the proper registry to affect third persons and property dealings (especially where real property is involved).

Post-marriage changes to the property regime are not freely allowed by mere agreement; Philippine law generally treats changes as exceptional and typically subject to strict statutory conditions and judicial safeguards (because creditors, heirs, and third parties may be affected).

3) Where “foreign law” can enter: the conflicts-of-law map

A foreign-law clause becomes relevant when the marriage settlement has a foreign element, for example:

One or both spouses are foreign nationals;
The settlement is signed abroad or the marriage is celebrated abroad;
The spouses will live abroad (domicile/habitual residence abroad);
The couple’s significant property is abroad; or
There is a mixed-nationality marriage (Filipino + foreigner).

Philippine conflict-of-laws analysis typically breaks the problem into separate questions, each potentially pointing to a different governing law:

Capacity to enter into the marriage settlement (and sometimes the marriage itself)
Formal validity (was it executed in the proper form?)
Essential validity / enforceability (are the substantive stipulations valid?)
Property classification and effects, especially for property located in the Philippines
Third-party effects (creditors, purchasers, heirs) and registration requirements

A foreign-law clause cannot collapse these categories into one. Philippine courts often treat them separately.

4) Party autonomy: Can spouses choose foreign law?

A. General principle: autonomy is recognized—but with family-law limits

Philippine law is not hostile to party autonomy in private international law. In contracts, a governing-law clause is often respected. But a marriage settlement is a status-adjacent instrument: it affects the marital property regime, family solidarity rules, and third parties. Because of that, Philippine law is more willing to say:

“You may agree on many financial arrangements,” but
“You may not use a foreign-law clause to defeat mandatory Philippine rules or public policy.”

So, whether spouses may choose foreign law depends heavily on:

Nationality of the parties,
Place of celebration of marriage,
Where the property is located (especially Philippine real property),
Whether the clause attempts to avoid mandatory Family Code defaults, and
Whether it prejudices third parties.

B. Practical categories (most common scenarios)

1) Two foreign spouses, marriage and settlement abroad, later dealing with the Philippines

This is the situation where a foreign-law clause has the strongest chance of being respected—as between the spouses—because Philippine public policy concerns are lower and the parties’ “personal law” is foreign.

However, even here, property located in the Philippines and transactions affecting third persons may still trigger Philippine mandatory rules (see Parts 6 and 7).

2) Filipino + foreign spouse (mixed marriage)

This is the most sensitive category. Philippine law contains strong policy rules tied to:

protection of the Filipino spouse,
predictability for third persons dealing with Filipino families,
constitutional restrictions (e.g., land ownership), and
Philippine family-policy defaults (e.g., the default property regime when there is no valid settlement).

In mixed marriages, a “foreign law governs everything” clause can be partially recognized (for example, as to certain obligations or arrangements) yet disregarded or cut back where it clashes with mandatory Philippine rules—particularly with respect to property in the Philippines and third-party effects.

3) Two Filipinos choosing foreign law

This is generally the weakest case for a foreign-law clause. Philippine conflict rules strongly attach many personal and family-law matters to Filipino citizens and Philippine public policy. A foreign-law choice that effectively evades Philippine mandatory family-property rules is vulnerable to being treated as ineffective to that extent.

5) The hard limits: what foreign law cannot override

Even if foreign law is chosen, Philippine law commonly insists on several non-negotiables.

A. Public policy in family relations

Philippine public policy is especially strong in matters touching on:

the marital relationship’s legal incidents,
support and family solidarity principles,
fraud on creditors,
rights of children, and
rules that are designed to protect third persons.

A foreign-law clause that authorizes stipulations considered impermissible under Philippine family policy may be refused enforcement in the Philippines.

B. Constitutional and land rules

No marriage settlement—Philippine-law-governed or foreign-law-governed—can validly do what the Constitution forbids. The classic example is ownership of Philippine land: foreign spouses cannot be granted ownership beyond what Philippine constitutional rules allow. A foreign-law clause cannot “import” a foreign community-property concept to confer forbidden land ownership in the Philippines.

C. Rules on fraud, simulation, and prejudice to creditors/third persons

Even if spouses agree privately, Philippine law protects:

existing creditors,
purchasers in good faith,
heirs whose legitimes and compulsory succession rights may be implicated through property maneuvers, and
the integrity of registries.

A clause designed to hide assets, defeat creditors, or manipulate ownership records risks invalidation or non-enforcement.

6) Formal validity: foreign execution vs Philippine requirements

A frequent mistake is thinking that a governing-law clause cures formal defects. It does not.

A. If executed in the Philippines

If the settlement is executed in the Philippines, Philippine authorities and courts will expect compliance with Philippine formalities (writing, proper execution, notarization standards, and registration norms where applicable).

B. If executed abroad

If executed abroad, Philippine practice typically recognizes that documents may follow the form allowed where executed, but you still face Philippine requirements for:

authentication/consularization/apostille (as applicable),
producing a legally usable copy for Philippine registries and courts, and
registration/annotation in relevant Philippine registries if the document will be invoked against third persons or to govern dealings with Philippine property.

In short: a foreign prenup may be a valid contract abroad, yet still be practically ineffective in the Philippines until properly proven and, where needed, recorded.

7) Property location matters: Philippine “lex situs” pressure

Even where Philippine courts are open to applying foreign law to aspects of marital property relations, there is a powerful counterweight:

A. Real property in the Philippines is strongly tied to Philippine law

As a traditional conflicts principle, rights in rem over immovable property (land and interests in land) are commonly governed by the law of the place where the property is situated. In the Philippines, this means:

transfers,
registrability,
forms of title,
allowable owners,
annotations affecting the property, are subject to Philippine law and registry rules.

So a foreign-law clause cannot reliably control:

whether a spouse may be placed on title,
whether a community-property regime can be registered as such on Philippine titles,
how third persons may rely on the registry, and
what incidents attach to land ownership under Philippine law.

B. Movables and intangibles are more flexible, but still policed by public policy

Bank accounts, shares, receivables, and movable assets can be more amenable to foreign-law treatment depending on where the asset is located or administered and how the dispute arises. But Philippine courts may still decline foreign-law application if it collides with:

mandatory family protections,
fraud/creditor rules,
succession constraints when a death occurs.

8) Essential validity: what clauses are typically vulnerable

Even assuming the correct governing law is foreign, Philippine enforcement can still fail for specific stipulations, especially those that:

Attempt to waive future support in a way Philippine policy does not allow
Undermine rights of children or legitimacy-related protections
Authorize clearly prohibited transfers, especially of Philippine land to a foreign spouse
Operate as a fraud on creditors
Contradict the statutory structure of matrimonial property regimes in a way Philippine law treats as impermissible (e.g., creating a regime that leaves one spouse effectively without any protection or recourse, depending on circumstances)

Philippine treatment is often “severability-like” in effect: the court may recognize the settlement generally while refusing enforcement of specific offending provisions, especially when third-party rights or public policy are implicated.

9) Proof of foreign law: the procedural reality that often decides the case

A foreign-law clause does not apply itself. In Philippine litigation, foreign law is generally treated as a fact that must be alleged and proven (typically through appropriate evidence such as official publications or expert testimony, depending on the context and the court’s evidentiary expectations).

If foreign law is not properly proven, Philippine courts often fall back on the practical doctrine that, in the absence of proof, the court will apply Philippine law (often described as a presumption that foreign law is the same as Philippine law, or simply a procedural default to Philippine law).

So even a carefully drafted foreign-law marriage settlement can end up being decided under Philippine law if the foreign law is not adequately pleaded and established in court.

10) Recognition vs enforcement: a crucial distinction

Even when a Philippine court “recognizes” that:

the spouses executed a valid agreement abroad, and
they intended foreign law to govern,

enforcement in the Philippines is still a second question. Enforcement can be denied or limited due to:

public policy,
constitutional/property restrictions,
third-party prejudice,
registry rules,
failure to prove foreign law, or
formal/registration deficiencies for Philippine property dealings.

Think of it as a two-stage filter:

Is there a valid agreement between the spouses?
Will Philippine institutions enforce it for the specific relief requested (property transfer, annotation, creditor opposition, estate settlement, etc.)?

11) Common drafting strategies in Philippine practice (and why they matter)

Where foreign elements exist, sophisticated marriage settlements often do not rely on a single sweeping clause (“This is governed by X law”). Instead they use layered drafting consistent with conflicts reality:

A. Split the issues

Personal/property regime framework: specify the intended regime and how assets/income are classified.
Situs-sensitive property: provide a Philippines-compliance section for Philippine real property (acknowledging constitutional limits and registry requirements).
Movables/intangibles: provide clearer choice-of-law treatment where it is more likely to be respected.
Administration and management: define management powers, but align with mandatory protections and creditor safeguards.

B. Add compliance and severability mechanisms

A clause stating that provisions will be interpreted to comply with mandatory Philippine law where applicable (especially on Philippine land and third-party matters).
Severability to preserve the rest of the settlement if a specific clause is struck down.

C. Build an evidence plan for foreign law

If foreign law is chosen, the settlement can anticipate later proof by:

identifying the foreign jurisdiction precisely,
referencing codal provisions conceptually (without assuming a Philippine court will judicially notice them),
and preparing the documentation chain needed for Philippine proceedings.

12) Bottom-line conclusions in Philippine context

Yes, spouses can attempt to choose foreign law, but a marriage settlement is not treated like a purely private commercial contract in the Philippines.
The effectiveness of a foreign-law clause is highly scenario-dependent, especially on nationality, place of marriage/settlement execution, and location/type of property.
Philippine public policy, constitutional limits (notably on land ownership), and third-party protections can override or limit foreign-law application.
Even where foreign law is theoretically applicable, it must usually be properly proven in Philippine proceedings, or Philippine law will likely be applied in practice.
For Philippine real property, Philippine law and registry rules exert dominant control regardless of a foreign-law clause.