Short answer. In favour of the employee. Article 4 of the Labor Code directs that all doubts in implementing and interpreting the Code and its rules be resolved in favour of labour. It is a tie-breaker, though, not a thumb on the scale: it applies only where the provision is genuinely doubtful.
What the law says
All doubts in the implementation and interpretation of the provisions of this Code, including its implementing rules and regulations, shall be resolved in favor of labor.
Labor Code, Article 4 — Doubts Resolved For Labor. Read the full provision →
The words the rule turns on
Article 4 is one sentence long: All doubts in the implementation and interpretation of the provisions of this Code, including its implementing rules and regulations, shall be resolved in favor of labor. Two things in that sentence do the work. The first is doubts — the rule is a tie-breaker for genuine ambiguity, not a general instruction that the worker wins. The second is its reach: not merely the Code itself but also the rules and regulations issued under it, so a doubtful implementing regulation is read the same way a doubtful statutory provision is.
What the rule does not do
The commonest misreading is that the employee prevails whenever the two sides disagree. The provision does not say that. It operates where, after reading the text and weighing what is actually before the decision-maker, the question is still genuinely balanced — where the words will carry two meanings, or the material points equally both ways. If a provision is clear it is applied as written, even where the result is hard on the worker; if the facts favour the employer they are found accordingly. A rule of construction settles ties. It does not decide the match.
Where the tie-breaker actually bites
The premise behind it is that the two sides of an employment relationship do not bargain from the same position, and that the Code was written to correct that imbalance rather than to sit neutrally above it. In practice the rule matters most where the drafting is old, generic or borrowed: a benefit granted in one clause and qualified in another, a coverage exclusion whose edges were never spelled out, a rule capable of being read to include or exclude a whole class of workers. Where the drafting left a gap, the gap closes in the worker's favour.
What settles it in your own case
Before the rule can help you, somebody has to identify the ambiguity precisely. That means the actual text: the provision or implementing rule you are relying on, the exact wording of the contract or company policy said to override it, and the payslips or notices showing how the employer has in fact been applying it. A consistent past practice often fixes the meaning without needing Article 4 at all. Bring the documents rather than a summary of them — the question is almost always what one particular sentence means, and that cannot be assessed from a description.