delivered the opinion of the Court.

In his petition for habeas corpus presented on his own right before the Superior Court, Arecibo Part, appellant challenged a sentence of 6 to 10 years’ imprisonment imposed on him for the crime of grand larceny, on the ground that there was not a wide enough margin of fluctuation between the fixed minimum of 6 years and the maximum of 10 years, for which reason the purposes of the Indeterminate Sentences Act would be defeated. 34 L.P.R.A. § § 1024-25. People v. Superior Court, 78 P.R.R. 135.

After a hearing the trial court denied the petition for habeas corpus without considering the merits of the question raised, on the ground that the petitioner would not start to serve the challenged sentence until December 20, 1963, according to the service of the writ, since he was serving a sentence of 1 to 3 years’ imprisonment imposed on him by the Superior Court, Ponce Part, for another crime of grand larceny, and before starting to serve the sentence of 6 to 10 years, which he challenged, he should also serve two other sentences imposed by the Superior Court, San Juan Part, of 1 to 3 years in the penitentiary for crimes of the same kind.

In the appeal, before us, through counsel appointed by this Court to represent him, appellant maintains that what he tries to obtain is an amendment of the challenged sentence, since the 6-year minimum violates the principle of indetermination and that sentence therefore being null, he may challenge the same by habeas corpus even though he has not started to serve the same.

*180Appellant is wrong. It should he a well-settled doctrine in this jurisdiction 1 that the writ of habeas corpus does not lie to set aside a sentence which has not yet been served due to the fact that petitioner is serving another sentence for which his imprisonment is lawful. The purpose of the writ is to investigate the lawfulness of the arrest with a view to granting the remedy of release from jail, if the same is illegal or of admitting him to bail in appropriate cases. The writ of habeas corpus may not be used as a means of securing judicial decisions which shall not affect petitioner’s custody or arrest. McNally v. Hill, Warden, 293 U.S. 131, 79 L. Ed. 238 (1934). Cf. Díaz v. Campos, 81 P.R.R. 975.

The trial court having acted correctly, the sentence is affirmed.