Short answer. Reclusion temporal. Article 124 of the Revised Penal Code imposes reclusion temporal on a public officer who, without legal grounds, detains a person for more than six months — the harshest of the four escalating penalties the article sets for arbitrary detention based on how long the detention lasted.
What the law says
That of reclusion temporal, if the detention shall have exceeded six months.
Revised Penal Code, Article 124 — Arbitrary Detention By Officers. Read the full provision →
What the law says
Any public officer or employee who, without legal grounds, detains a person, shall suffer
Revised Penal Code, Article 124 — Arbitrary Detention By Officers. Read the full provision →
Reclusion temporal for detention beyond six months
Article 124 provides that a public officer or employee who, without legal grounds, detains a person shall suffer that of reclusion temporal, if the detention shall have exceeded six months. Reclusion temporal runs from twelve years and one day up to twenty years, making it by far the heaviest of the penalties this article imposes, reserved specifically for detentions that go on longest without legal grounds. Once the detention crossed the six-month line, that single fact is what selects this bracket.
How the penalty scales with the length of detention
Article 124 sets four escalating penalties tied directly to how long the unlawful detention lasted: arresto mayor in its maximum period to prision correccional in its minimum period for detention of up to three days; prision correccional in its medium and maximum periods for detention of more than three but not more than fifteen days; prision mayor for detention of more than fifteen days but not more than six months; and reclusion temporal once the detention exceeds six months. Each additional bracket of time crossed moves the offense into a substantially heavier penalty.
What makes the detention unlawful in the first place
All of these penalties apply specifically to detention carried out without legal grounds. The article separately provides that the commission of a crime, or violent insanity or another ailment requiring compulsory hospital confinement, counts as a legal ground for detention — so the escalating penalties described here are for detention that lacks any such justification, not for every instance of a person being held by an officer.
What the article does not resolve
Article 124 fixes the penalty once the length of an unlawful detention is established, but it does not itself set out how the length of detention is calculated, what evidence establishes when it began and ended, or how the absence of legal grounds is to be proven in a given case. Those questions depend on the specific facts of the detention being examined. Note also that the offender this article names is a public officer or employee; a private person who unlawfully detains someone answers under different provisions of the Code rather than this one.