Short answer. Whether a defect in one item affects the rest of a batch depends on the same rules that govern animals sold together — if the items are sold as a unit and the defect in one piece renders the purchase fundamentally flawed, the buyer may have grounds to act on the whole lot, not just the defective item.
What the law says
The provisions of the preceding article with respect to the sale of animals shall in like manner be applicable to the sale of other things.
Civil Code, Article 1573 — Rule Extended to Other Things. Read the full provision →
The animal rules apply to goods generally
Article 1573 of the Civil Code is a bridging provision. It takes the rules governing redhibitory defects in animal sales — particularly the rules about batches and groups sold together — and extends them in like manner to the sale of other things. This means the framework developed for livestock transactions applies equally when you buy a lot of merchandise, a set of goods, or a bundle of items in a single transaction. The principle is the same: the seller must deliver goods that are free from hidden defects that would render them unfit for their purpose.
How the batch rule works
Under the animal rules incorporated by Article 1573, the key question when a batch is sold together is whether the items were sold as an indivisible unit or as separate individual pieces. If they were sold as a unit — meaning the price was set for the whole lot and you had no practical way to buy one piece without the others — then a defect in one piece can entitle you to rescind the entire purchase. If, on the other hand, the items were essentially sold separately even though they happened to be in the same transaction, the defect in one does not automatically infect the others.
The defect must be a qualifying hidden defect
Not every flaw in a product triggers redhibition. The defect must be hidden — meaning it was not apparent at the time of sale, and you could not have discovered it through ordinary inspection. It must also have existed at the time of sale, not developed afterward due to normal use or negligence. And it must be significant enough to render the thing unfit for its intended use, or to sufficiently diminish its usefulness that you would not have bought it — or would have paid much less — had you known. A superficial or minor imperfection does not meet this standard.
Your two options — rescission or price reduction
If the defect qualifies, the Civil Code generally gives the buyer a choice between two remedies. You may pursue rescission — returning the defective goods and getting your money back — or you may pursue an accion quanti minoris, a reduction in the price to reflect the defect while keeping the goods. Which remedy applies to your specific batch purchase, and whether the defect in one item justifies rescinding the whole purchase or only a partial refund, depends on the nature of the goods, how they were sold, and the severity of the defect. These are facts-specific questions.