In probate proceedings, the scope of the court's inquiry is limited to questions on the extrinsic validity of the will.

The general rule is that in probate proceedings, the scope of the court's inquiry is limited to questions on the extrinsic validity of the will; the probate court will only determine the will's formal validity and due execution. However, this rule is not inflexible and absolute. It is not beyond the probate court's jurisdiction to pass upon the intrinsic validity of the will when so warranted by exceptional circumstances. When practical considerations demand that the intrinsic validity of the will be passed upon even before it is probated, the probate court should meet the issue.
Thus, the probate court can resolve the issue of preterition considering that the will does not contain specific legacies or devises since the effect of preterition is the annulment of the institution of heirs. The annulment effectively caused the total abrogation of the will, resulting in total intestacy of the inheritance. The decedent's will, no matter how valid it may appear extrinsically, is null and void. The conduct of separate proceedings to determine the intrinsic validity of its testamentary provisions would be superfluous. (G.R. No. 198994, February 03, 2016)