THE REMEDY OF WRIT OF HABEAS CORPUS:

Essentially, a writ of habeas corpus applies to all cases of illegal confinement or detention by which any person is deprived of his liberty. (Moncupa v. Enrile, 225 Phil. 191, 197 (1986).  Rule 102 of the 1997 Rules of Court sets forth the procedure to be followed in the issuance of the writ. x x x  The objective of the writ is to determine whether the confinement or detention is valid or lawful. If it is, the writ cannot be issued. What is to be inquired into is the legality of a person's detention as of, at the earliest, the filing of the application for the writ of habeas corpus, for even if the detention is at its inception illegal, it may, by reason of some supervening events, such as the instances mentioned in Section 4 of Rule 102, be no longer illegal at the time of the filing of the application. (Go, Sr. v. Ramos, G.R. No. 167569, 4 September 2009, 598 SCRA 266, 301).

Plainly stated, the writ obtains immediate relief for those who have been illegally confined or imprisoned without sufficient cause. The writ, however, should not be issued when the custody over the person is by virtue of a judicial process or a valid judgment.  The most basic criterion for the issuance of the writ, therefore, is that the individual seeking such relief is illegally deprived of his freedom of movement or placed under some form of illegal restraint. If an individual's liberty is restrained via some legal process, the writ of habeas corpus is unavailing. (In Re: The Writ of Habeas Corpus for Reynaldo De Villa, G.R. No. 158802, 17 November 2004, 442 SCRA 706, 719).

Fundamentally, in order to justify the grant of the writ of habeas corpus, the restraint of liberty must be in the nature of an illegal and involuntary deprivation of freedom of action. (Veluz v. Villanueva, G.R. No. 169482, 29 January 2008, 543 SCRA 63, 67-68).

In general, the purpose of the writ of habeas corpus is to determine whether or not a particular person is legally held. A prime specification of an application for a writ of habeas corpus, in fact, is an actual and effective, and not merely nominal or moral, illegal restraint of liberty. The writ of habeas corpus was devised and exists as a speedy and effectual remedy to relieve persons from unlawful restraint, and as the best and only sufficient defense of personal freedom. A prime specification of an application for a writ of habeas corpus is restraint of liberty. The essential object and purpose of the writ of habeas corpus is to inquire into all manner of involuntary restraint as distinguished from voluntary, and to relieve a person therefrom if such restraint is illegal. Any restraint which will preclude freedom of action is sufficient. In passing upon a petition for habeas corpus, a court or judge must first inquire into whether the petitioner is being restrained of his liberty. If he is not, the writ will be refused. Inquiry into the cause of detention will proceed only where such restraint exists. If the alleged cause is thereafter found to be unlawful, then the writ should be granted and the petitioner discharged. 

Needless to state, if otherwise, again the writ will be refused. While habeas corpus is a writ of right, it will not issue as a matter of course or as a mere perfunctory operation on the filing of the petition. Judicial discretion is called for in its issuance and it must be clear to the judge to whom the petition is presented that, prima facie, the petitioner is entitled to the writ. It is only if the court is satisfied that a person is being unlawfully restrained of his liberty will the petition for habeas corpus be granted. If the respondents are not detaining or restraining the applicant or the person in whose behalf the petition is filed, the petition should be dismissed (NURHIDA JUHURI AMPATUAN vs. JUDGE VIRGILIO V. MACARAIG, G.R. No. 182497, June 29, 2010, PEREZ, J.).