Short answer. Institution of heir is the act, in a will, by which the testator designates the person or persons who are to succeed to his property and transmissible rights and obligations. It is the clause that says who inherits — the naming act that turns a chosen person into an heir under that will.
What the law says
Institution of heir is an act by virtue of which a testator designates in his will the person or persons who are to succeed him in his property and transmissible rights and obligations.
Civil Code, Article 840 — Institution of Heir Defined. Read the full provision →
The naming act, defined
Article 840 defines institution of heir plainly: it is an act by virtue of which a testator designates in his will the person or persons who are to succeed him in his property and transmissible rights and obligations. Stripped of the legal phrasing, it is the part of a will where the testator says, in effect, "this is who takes my place." Everything else in a will — the description of the property, the conditions attached, the shares given — builds on this one act. Without an institution, there is no one designated to succeed at all.
What passes to the person designated
The article is specific about what an heir succeeds to: the testator's property and his transmissible rights and obligations. That word matters. Not everything a person holds during life carries over — purely personal rights and obligations, tied to the testator himself, are not what institution transfers. What Article 840 contemplates is the estate in the broader sense: assets, and the rights and obligations attached to them that are capable of passing to someone else after death.
One heir, or several
The definition allows for the person or persons to be designated, so institution is not limited to naming a single successor. A testator may institute one heir to the whole estate, or several heirs together, with the will then dividing the property and rights among them. The act of institution is the same regardless of number — it is the naming of who is to succeed, whether that turns out to be one person or many.
Why this matters when a will is read
Because institution is the operative naming act, it is usually the first thing to look for when reading a will and the first thing that gets tested when a will is contested. A person is an heir under a particular will because they were designated in it under Article 840 — not because they are a relative, and not automatically because they expected to inherit. Anyone trying to understand who a will actually favors should start by identifying exactly who was designated, and for what, before looking at conditions or shares.