Short answer. Generally, no. Rule 102, Section 4 forbids the writ where the person is in the custody of an officer under process issued by a court or judge with jurisdiction, and it does not authorise the discharge of a person charged with or convicted of an offence, or imprisoned under lawful judgment.
What the law says
and that the court or judge had jurisdiction to issue the process, render the judgment, or make the order, the writ shall not be allowed
Rule 102, Section 4 — When writ not allowed or discharge authorized. Read the full provision →
What the law says
Nor shall anything in this rule be held to authorize the discharge of a person charged with or convicted of an offense in the Philippines, or of a person suffering imprisonment under lawful judgment.
Rule 102, Section 4 — When writ not allowed or discharge authorized. Read the full provision →
Custody under court process is outside the writ
Rule 102, Section 4 draws the line at judicial authority. Where the person restrained is in the custody of an officer under process issued by a court or judge, or by virtue of a judgment or order of a court of record, and that the court or judge had jurisdiction to issue the process, render the judgment, or make the order, the writ shall not be allowed. Habeas corpus attacks detention without lawful authority; a court order from a court with jurisdiction is lawful authority. The writ is not a way around a warrant, a commitment order or a judgment of conviction.
Jurisdiction is the hinge, not correctness
What the rule makes decisive is whether the issuing court had jurisdiction — the power to act — not whether it acted well. The section adds that if jurisdiction appears after the writ is allowed, the person shall not be discharged by reason of any informality or defect in the process, judgment, or order. So a badly worded warrant, a procedural slip, an order you believe wrong on the merits: none of these is a ground for release by habeas corpus. Complaints of that kind belong in the case itself, before the court that issued the order, through the remedies that case provides.
Charged, convicted, or serving sentence
The section then closes the door explicitly on the situation the question describes: Nor shall anything in this rule be held to authorize the discharge of a person charged with or convicted of an offense in the Philippines, or of a person suffering imprisonment under lawful judgment. A relative serving sentence after conviction is imprisoned under a judgment, and the rule refuses to treat habeas corpus as a substitute for appeal or any other remedy against that judgment. The same is true of someone detained on a pending criminal charge — being charged is itself within the exclusion.
Where the writ still does its work
None of this makes the writ useless; it defines its home ground. Habeas corpus is aimed at detention that rests on no valid process at all — a person held without any charge, order or judgment, or held under process from a body that had no jurisdiction to issue it. If your family member is detained under a court order, the questions a lawyer will ask first are which court issued it and whether that court had power over the case and the person. If the answer is that jurisdiction existed, the fight must be fought inside that case, not through a petition for the writ.