A man dies widowed, with no descendants or ascendants, and leaves a will naming as his sole and universal heir whoever has personally cared for him during the last years of his life. He appoints a friend as executor, granting him the power to determine who that person is.
The testator’s siblings question the validity of this clause and of the power granted to the executor, arguing that it could violate Article 670 of the Spanish Civil Code, which states that a will is a strictly personal act and cannot be left, in whole or in part, to the discretion of a third party.

Art. 670 CC:
“A will is a strictly personal act: its formation may not be left, in whole or in part, to the discretion of a third party, nor may it be executed through an attorney or representative. Nor may the subsistence of the appointment of heirs or legatees, nor the designation of the portions in which they shall inherit when they are instituted by name, be left to the discretion of a third party.”

Answer:

We consider that this principle is not violated, and that the designation of the heir in the manner established by the testator is valid, because the testator’s will is the supreme rule in succession, provided that it does not infringe forced heirship (legítimas), which does not arise in this case.

Articles 750 and 772 of the Spanish Civil Code allow the testator to:

• Specify criteria for determining the heir, and
• Entrust to a third party the task of identifying the person who meets those criteria,

as long as the third party does not exercise discretionary or creative power to choose an heir arbitrarily.

In this case, the executor does not choose the heir; he merely identifies the person who in fact cared for the deceased, according to the factual condition objectively described by the testator.

Therefore:

• The heir is designated by the testator,
• The executor’s role is one of verification, not discretionary appointment, and
• The clause is perfectly valid under Spanish succession law.