Short answer. Yes. Under Article 691 of the Civil Code, all co-owners must consent before a voluntary easement can be imposed on co-owned land. If only some consent, the easement is held in abeyance until every co-owner has agreed. A lone co-owner who grants an easement binds only themselves, not the whole property.
What the law says
In order to impose an easement on an undivided tenement, or piece of land, the consent of all the co-owners shall be required.
Civil Code, Article 691 — Consent Of All Co-Owners. Read the full provision →
The rule: every co-owner must say yes
Article 691 of the Civil Code is clear: imposing an easement on co-owned, undivided land requires the consent of all the co-owners. This is not a majority vote. It is not enough that three out of four siblings agree. Until the last co-owner has expressed conformity, the easement simply does not attach to the property as a whole. The consent of some is held in abeyance — it is not wasted, but it is incomplete.
What happens when only some co-owners agree
If one co-owner signs an easement agreement without the others, the law does not void that act entirely. Instead, it binds that co-owner and their successors personally — they cannot later try to prevent the grantee from exercising whatever right was promised. But the easement does not become a real burden on the property until every co-owner has given conformity. The grantee is left in a frustrating middle ground: the agreeing co-owner is personally stopped from objecting, but the easement cannot be enforced against the property or the other co-owners who never consented.
Practical situation: what to do if one co-owner refuses
If you are trying to grant or obtain an easement over co-owned land and one co-owner simply refuses to cooperate, the voluntary route is blocked. You cannot proceed as if their share does not exist. Your options narrow considerably: you could attempt to buy out the refusing co-owner's share, wait until the co-ownership is partitioned and the relevant portion falls to a co-owner who agrees, or explore whether any legal or compulsory easement (rather than a voluntary one) might cover your situation under a different rule. A situation that looks like a voluntary easement problem may sometimes have an alternative path, but only a proper review of your specific facts can tell you which.
Why the rule exists
Co-ownership means every co-owner holds a proportional, undivided interest in the whole. An easement is a real right — it runs with the land and burdens every co-owner's share. Allowing a single co-owner to impose that burden without the others' agreement would effectively let one person diminish the value and use of property that belongs to several. The unanimity requirement protects each co-owner's interest in the undivided whole until partition gives each person clear individual rights over a definite portion.