Short answer. Anyone who can both enter into contracts and dispose of their property may make a donation. Article 735 of the Civil Code ties the power to give to two capacities together — the general capacity to contract and the specific power to dispose of the particular property being given away.
What the law says
All persons who may contract and dispose of their property may make a donation.
Civil Code, Article 735 — Who May Make A Donation. Read the full provision →
Two capacities, not one
Article 735 is short but demanding: All persons who may contract and dispose of their property may make a donation. It requires two things at once. First, the general capacity to contract — the giver must be of the age and mental competence the law requires to bind himself in an agreement. Second, the power to dispose of the specific property — the giver must have the right to part with that particular thing. A donation is an act of liberality that transfers ownership, so the law asks both that the donor can validly act and that the property is truly his to give.
Why capacity to contract is measured at the right time
Because a donation is a serious, often irrevocable, act, the donor's capacity to contract is judged at the time the donation is made. A person who lacks contractual capacity then — for reasons the law recognises, such as being a minor or being unable to give intelligent consent — cannot make a valid donation, even if the gift seems generous or well-intentioned. This protects people who cannot fully understand what they are giving up. It also protects their families and creditors from having assets stripped away by someone not in a position to decide.
The power to dispose of the property
Capacity to contract is not enough on its own; the donor must also be able to dispose of the particular property. Someone who does not own the thing, or whose ownership is restricted, cannot give away more than he holds. Property that is reserved, held in trust, or subject to another's rights may be beyond the donor's power to donate freely. The requirement keeps donations from becoming a way to hand over what is not really one's to give, which would prejudice the true owner or those with claims on the property.
What this provision does not cover
Article 735 sets who may donate; it does not, by itself, tell you whether a specific gift is valid. Separate rules govern who may receive a donation, the form a donation must take (a gift of real property, for instance, requires a public instrument), and how much a person may give without impairing the legitime of compulsory heirs. A donor may be perfectly capable yet still see a gift reduced or refused for one of those reasons. Because a donation can be hard to undo, confirming both capacity and the correct form with counsel before signing is prudent.