Short answer. You can claim the inheritance now by giving a security — the mechanism known as the caucion muciana. Article 879 of the Civil Code allows you to receive the inheritance immediately in exchange for a bond or guarantee that you will return it, with fruits and interest, if you ever violate the condition.
What the law says
he shall comply by giving a security that he will not do or give that which has been prohibited by the testator, and that in case of contravention he will return whatever he may have received, together with its fruits and interests.
Civil Code, Article 879 — Negative Potestative Conditions (Caucion Muciana). Read the full provision →
The problem with a negative condition
A will that says 'I leave you my estate provided you never practice medicine' imposes a negative potestative condition — a condition that depends on you not doing something. The difficulty is obvious: you can only definitively prove you never practiced medicine on the day you die, which is too late to be useful. The Civil Code recognizes this and provides a practical solution so heirs are not left waiting indefinitely for an inheritance they can never actually receive.
The caucion muciana: security instead of waiting
Article 879 resolves the problem with a mechanism called the caucion muciana, a guarantee you furnish in place of actual compliance. The article states that if the potestative condition is negative, the heir shall comply by giving a security that he will not do or give that which has been prohibited by the testator, and that in case of contravention he will return whatever he may have received, together with its fruits and interests. In practical terms, you post a bond or provide some other form of security, and you receive the estate now. The security is the substitute for proof of a condition that cannot be definitively confirmed until your death.
What happens if you eventually break the condition
The security is not just a formality — it is an enforceable guarantee. If you later violate the prohibition (say, you eventually do practice the forbidden profession), the security becomes the mechanism by which you restore what you received. You would be required to return the inheritance itself along with all fruits and interest it generated during the time you held it. The testator's wish is therefore honored: the estate goes back if you break the condition, and the security makes that enforcement possible.
Practical considerations for heirs
The form and amount of security adequate for a caucion muciana depends on the value of the estate and the nature of the obligation being guaranteed. This is typically worked out in the context of estate settlement proceedings, and the court or the parties to the settlement determine what security is sufficient. If other heirs are involved, they have an interest in ensuring the security is adequate to protect their position if the condition is eventually broken. Taking early legal advice on what form of security will satisfy the requirement can prevent disputes during the settlement process.