Short answer. No. Under Article 1899, if a duly authorized agent acts in accordance with the principal's orders, the principal cannot set up the ignorance of the agent as to circumstances the principal himself was, or ought to have been, aware of. You cannot escape a deal by hiding behind what your agent did not know but you did.
What the law says
the latter cannot set up the ignorance of the agent as to circumstances whereof he himself was, or ought to have been, aware.
Civil Code, Article 1899 — Principal Cannot Plead Agent's Ignorance. Read the full provision →
You cannot hide behind your agent's ignorance
A principal cannot use his agent as a shield for his own knowledge. Article 1899 provides that if a duly authorized agent acts in accordance with the orders of the principal, the latter cannot set up the ignorance of the agent as to circumstances whereof he himself was, or ought to have been, aware. So where the agent did exactly as the principal told him, the principal cannot later avoid the transaction by arguing that the agent did not know some relevant fact — if the principal himself knew that fact, or should have.
'Was, or ought to have been, aware'
The rule reaches not just what the principal actually knew, but what he ought to have been aware of. So a principal cannot cultivate ignorance and rely on it either — if he should have known a circumstance, in the exercise of ordinary diligence, he is treated as if he did. This closes an obvious gap: otherwise a principal could avoid knowing inconvenient facts, instruct his agent, and then plead the agent's ignorance of what he had deliberately not looked into. The article ties the outcome to the principal's real or constructive knowledge, because he is the one directing the deal.
It applies when the agent followed orders
The rule is framed around a specific situation: the agent was duly authorised and acted in accordance with the principal's orders. That framing matters. Where the agent did as he was told, his own state of knowledge is beside the point — he was the instrument, and the principal's knowledge governs. This is different from a case where the agent went off on his own, exceeded his authority, or exercised his own judgement; there, other rules about the agent's conduct come into play.
The practical point
If you are tempted to unwind a deal by saying your agent did not know something, first ask whether you knew it, or should have. If you did, this article closes that door — you cannot plead your agent's ignorance of what you were aware of. So the honest course is to give your agent the facts you have before he acts, both to protect the deal and to avoid a false hope of escape later. And if you are on the other side, dealing with someone's agent, take some comfort: the principal cannot later escape by pretending his agent's ignorance excused a transaction the principal himself understood.