Short answer. Yes. The Labor Code protects any employee who has filed a complaint or instituted a proceeding, without conditioning that protection on the complaint eventually succeeding. The retaliation ban attaches to the act of filing or testifying itself, not to whether your claim is ultimately upheld.
What the law says
It shall be unlawful for an employer to refuse to pay or reduce the wages and benefits, discharge or in any manner discriminate against any employee who has filed any complaint or instituted any proceeding under this Title or has testified or is about to testify in such proceedings.
Labor Code, Article 118 — Retaliation Prohibited. Read the full provision →
The protection does not mention outcome at all
Article 118 protects any employee who has filed any complaint or instituted any proceeding under this Title or has testified or is about to testify in such proceedings. Nowhere in that description does the article require the complaint to succeed, be found meritorious, or result in any particular ruling. The trigger for protection is the act of filing, instituting, testifying, or being about to testify — full stop, with no outcome-based qualifier attached to it.
Why that silence is significant
If the legislature had wanted to limit protection to employees whose complaints prevail, the article would need to say so, since that is a meaningful restriction, not a detail an article would leave to be assumed. Article 118 simply does not include any such condition. Reading a success requirement into the article would add words that are not there, when the article's actual test is only whether the complaint or proceeding was filed, instituted, or testified in or about to be testified in.
What the retaliation ban actually targets
The article forbids an employer from refusing to pay or reducing wages and benefits, discharging, or discriminating in any manner against you because you filed or testified. That prohibition is aimed at the employer's reaction to the act of complaining, not at policing whether your underlying claim was correct. An employer retaliating because your complaint eventually lost is still reacting to the fact that you complained, which is exactly what Article 118 addresses.
What to keep in mind either way
Even where your complaint did not succeed, Article 118's protection against retaliation stands on its own, separate from the merits of the underlying claim. Keep records of the timeline — when you filed or testified, and when any adverse treatment followed — since that sequence is what shows retaliation regardless of how the original complaint was eventually resolved. The outcome of your original complaint is simply not part of what this article asks a decision-maker to weigh.