Short answer. Yes, it is presumed fraudulent. Article 1387 provides that a sale, an alienation by onerous title, is presumed to defraud creditors when made by someone against whom a judgment has already been rendered. The judgment does not even need to concern the property sold or have been obtained by you.
What the law says
Alienations by onerous title are also presumed fraudulent when made by persons against whom some judgment has been rendered in any instance or some writ of attachment has been issued.
Civil Code, Article 1387 — When an Alienation Is Presumed to Defraud Creditors. Read the full provision →
What the law says
The decision or attachment need not refer to the property alienated, and need not have been obtained by the party seeking the rescission.
Civil Code, Article 1387 — When an Alienation Is Presumed to Defraud Creditors. Read the full provision →
The presumption for a sale made after judgment
A sale is what the law calls an alienation by onerous title, since the debtor receives something in exchange for the property. Article 1387 addresses this directly: alienations by onerous title are also presumed fraudulent when made by persons against whom some judgment has been rendered in any instance or some writ of attachment has been issued. Once a judgment already exists against your debtor, any sale he then makes of his property carries a legal presumption of fraud against his creditors, including you. You do not have to start from scratch proving intent to defraud.
The judgment need not be yours or about this property
The presumption is broader than many people expect. Article 1387 specifies that the decision or attachment need not refer to the property alienated, and need not have been obtained by the party seeking the rescission. So even if the judgment against your debtor came from an entirely different lawsuit brought by a different creditor, and even if that judgment says nothing about the particular property he later sold, the presumption still applies. You can rely on it as the creditor seeking to undo the sale, whether or not you were the one who won that earlier judgment.
What a presumption actually does for you
A presumption of fraud shifts the practical burden in your favor. Rather than you having to affirmatively prove your debtor intended to cheat his creditors, the law already treats the sale as fraudulent once the timing lines up with an existing judgment. Your debtor, or the buyer defending the sale, would be the one left to show that the transaction was not in fraud of creditors at all. That is a meaningfully different position than starting a case with no presumption in your favor and having to build the fraud case from the ground up.
The presumption is not the only way to prove fraud
Article 1387 also makes clear that its presumptions are not the exclusive route: "the design to defraud creditors may be proved in any other manner recognized by the law of evidence." So even outside the specific situation of a judgment or a writ of attachment already existing, other evidence of an intent to defraud can still support an action, though it would then need to be established rather than simply presumed. Knowing which route applies to your facts, the presumption or independent proof, affects how the case against the sale is best built.