The Doctrine of Aliud Pro Alio in B2B Transactions
Tuesday, December 30, 2025
Communications team
In the architecture of modern commerce, operational efficiency is built on the presumption of quality. When a corporation acquires an automated production line, a fleet of logistics vehicles, or a batch of critical raw materials, it is not merely purchasing a physical object; it is acquiring an expectation of functionality, performance, and future profitability. However, industrial reality is imperfect. The emergence of latent defects, design flaws, or technical nonconformities in business-to-business (B2B) transactions does not merely constitute a logistical inconvenience—it triggers one of the most severe, complex, and often relentless legal regimes in the Spanish and European legal systems.
Unlike Consumer Law, where the legislator extends a protective shield over the end user based on their presumed vulnerability, Commercial Law operates under the premise of equal footing. It is assumed that the parties are professionals, experts in their field, and equipped with the diligence necessary to audit their purchases. This assumption has devastating consequences for the unprepared business owner: claim periods that expire in a matter of days, fiendish evidentiary burdens, and a doctrinal distinction between “latent defect” and “delivery of a different thing” (aliud pro alio) that can mean the difference between recovering a multimillion-dollar investment or absorbing a catastrophic loss.
Article Content
This technical report, designed for corporate legal advisors, financial directors, and operations managers, dissects the legal anatomy of breach in commercial sales. Through an in-depth analysis of the most recent case law from the Supreme Court and Provincial Courts, and by comparing regional regulations such as the Civil Code of Catalonia with Common Law, it provides a roadmap for transforming legal uncertainty into a competitive strategic advantage. The objective is not only theoretical understanding but also the capacity to detect risks early and execute precise procedural maneuvers that ensure the viability of the business.
The Regulatory Duality and the Professional Standard of Diligence
The first barrier any business claim faces is the correct identification of the legal framework. In Spain, sales are not a monolithic institution; their regulation splits depending on the nature of the contracting parties and the intended use of the goods. Understanding this duality is the first step to avoid dismissal of a claim due to formal defects.
The Commercial Nature of Sales and the Exclusion of the Consumer
The Commercial Code (CCom) acts as the special rule that displaces the Civil Code (CC) in transactions between businesses. According to Article 325 of the CCom, the sale of movable goods for resale—either in the same form in which they were purchased or in a different form, with the intent of profiting from the resale—is considered commercial. However, case law has extended this concept to purchases of capital goods for the production process, understanding that even if the machine is not resold, it becomes part of a value chain aimed at generating profit.
This distinction is critical because the Civil Code, in its Article 1484, defines a latent defect as one that makes the item unfit for its intended use or diminishes its utility to such an extent that the buyer would not have purchased it. However, in the B2B environment, this standard is stricter. It is not enough for the defect to be invisible to the eye; it must be undetectable to an expert.
The Myth of the “Latent” Defect vs. the Expert Buyer
One of the most common points of friction in courts is the technical qualification of the buyer. Article 1484 of the Civil Code exempts the seller from liability for defects that, although not visible, should be known by the buyer “by reason of their trade or profession.”
In forensic practice, this raises the threshold of required diligence (lex artis) to extreme levels. If a transport company acquires used trucks and later claims excessive wear on the differentials, the court will likely dismiss the claim, arguing that a company in the transport sector has the technical capacity (or the duty to hire it) to inspect these components before purchase. “Concealment” in commercial transactions is not merely physical; it is technical. For a defect to be compensable between professionals, it must be so sophisticated or located in areas so inaccessible that even a standard Due Diligence performed by a competent expert could not have revealed it.
Type of Buyer
Standard of Diligence (Case Law)
Example of a Claimable Defect
Example of a Non-Claimable Defect
Individual (C2C)
Ordinary diligence of a “reasonable person.”
Moisture behind a built-in wardrobe.
A visible crack in the wall.
General Company (B2B)
Generic professional diligence. Duty of basic inspection.
Failure in the motherboard of a CNC machine after one month of use.
Dents in the exterior casing visible upon delivery.
Specialist Company (Expert Buyer)
Qualified technical diligence. Presumption of expert knowledge.
Internal microcracks in alloys detectable only with ultrasound.
Wear of sacrificial parts or mechanical failures detectable through noise or vibration during testing.
The Tyranny of Deadlines: Expiration and Procedural Strategy
If the standard of diligence is the qualitative filter, the deadlines in the Commercial Code are the temporal filter, designed to provide speed and legal certainty in commercial transactions. The vast majority of B2B claims fail not due to lack of merit, but due to untimeliness. Managing these timelines should be considered a risk management priority, not a mere administrative formality.
The Four-Day Ultimatum: Manifest Defects
Article 336 of the Commercial Code establishes a draconian four-day period from the receipt of goods to file a claim for defects in quality or quantity when the goods are delivered packaged. If the goods are received “in plain view” (unpackaged), the claim must be made immediately.
This period has the nature of a statute of expiration. If four days pass without a formal complaint, it is presumed iuris et de iure that the goods were accepted in full conformity. In modern logistics, this poses immense challenges. A company receiving 50 containers of electronic components often lacks the capacity to inspect the shipment within 96 hours. Nevertheless, the law is relentless. Case law, however, allows that the complaint can be general within the period, reserving the exact quantification of the damage for a later time, as long as the nonconformity is documented.
The 30-Day Trap: Article 342 of the Commercial Code
For internal (latent) defects, Article 342 of the CCom extends the complaint period to 30 days from delivery. This is the “complaint period,” a sine qua non procedural requirement to subsequently file a lawsuit.
The interpretation of the dies a quo (start date) is vital. Although the rule refers to “delivery,” modern case law, in an attempt to balance substantive justice, tends to calculate this period from when the defect “could have been discovered” by the buyer, especially for complex machinery requiring installation and commissioning. If a machine is delivered on January 1 but not installed until March 1, and the defect appears on March 15, courts usually accept that the 30-day period begins on March 15. However, relying on this flexible interpretation is a high-risk strategy. The unvarying legal recommendation is to notify any anomaly via burofax or notarial channel at the first sign of a defect.
The Expiration of Legal Action: The Six Months under Article 1490 CC
Once the complaint has been made within the 30-day period, the buyer has six months to file a lawsuit, according to Article 1490 of the Civil Code.
Here lies one of the most dangerous traps of the Spanish system. The prevailing doctrine and the case law of the Supreme Court consider this six-month period to be one of expiration, not of prescription.
Crucial Difference
Prescription can be interrupted (by burofax, email, or acknowledgment of debt), and the clock resets to zero. Expiration, however, cannot be interrupted extrajudicially. The six-month clock runs inexorably from the date of delivery. Friendly negotiations, promises of repair by the seller, or sending technicians to inspect the machine do not stop the expiration period.
Consequence
Many companies lose their right to sue because they spend five months trying to negotiate an amicable solution. By the seventh month, when negotiations fail, the legal action has already expired.
The Doctrine of Aliud Pro Alio: The Jurisprudential Escape Valve
Given the severity of the latent defect regime (30-day complaint period, six-month lawsuit period), the Supreme Court’s case law has developed a doctrinal framework that allows buyers to bypass these temporal barriers and access the general regime for contractual breach (5 years under common law, 10 in Catalonia). This doctrine is known as aliud pro alio, which literally means “one thing for another.”
Anatomy of Total Breach
Aliud pro alio arises when the defect is of such magnitude that we are not dealing with a “defective item,” but with a “different item” from what was agreed upon. It is not a matter of qualitative nonconformity, but of the absolute inability of the object to fulfill the purpose for which it was acquired.
The Supreme Court, in landmark rulings such as the January 17, 2008 decision and more recent resolutions from 2022 and 2023, has outlined two categories of aliud pro alio:
Material
A different substance from the one agreed upon is delivered (e.g., virgin olive oil is sold, but a pomace blend is delivered). This is uncommon in complex machinery.
Functional
The item delivered is physically as agreed, but it is completely unfit for its intended use, causing total dissatisfaction for the buyer.
Functional unfitness in industrial machinery
In the context of machinery and capital goods, the distinction between latent defect (imperfection) and aliud pro alio (uselessness) is the central battleground.
- Practical Example: A plastic injection machine that has occasional oil leaks and produces a 5% loss has latent defects (repairable, compensable via quanti minoris). A machine that, due to a design error in the control software, locks up every 10 minutes preventing continuous production constitutes an aliud pro alio.
- Case Law Criterion: The ruling of the Provincial Court of Barcelona on the Daewoo lathe case illustrates that unfitness does not have to be physical (the machine powers on) but can be economic and functional. If repairs are so frequent that they make the economic use of the asset unviable, it is considered a total breach.
Procedural Advantages of Aliud Pro Alio
Successfully invoking this doctrine radically transforms the legal landscape:
- Prescription Period: It shifts from the 6-month expiration period (latent defects) to the 5-year prescription under Article 1964 of the Civil Code (personal actions) following the 2015 reform.
- Remedies: It allows for contract termination (return of the price + interest) and full compensation for damages (lost profits, actual damages) under Articles 1124 and 1101 of the Civil Code, without the caps that often limit the redhibitory action.
The Catalan Exception: A 10-Year Prescription Oasis
In the complex Spanish legal landscape, Catalonia represents a highly significant protective anomaly for businesses. The coexistence of the Catalan Civil Code (CCCat) with state law creates asymmetries that must be strategically leveraged.
Article 121-20 of the CCCat and the Ten-Year Prescription
While in the rest of Spain the general prescription for contractual actions was reduced from 15 to 5 years in October 2015, Catalonia maintains in its Article 121-20 a general ten-year prescription period for all claims that do not have a specifically established term.
This difference is staggering. In a contract for the supply of industrial machinery governed by Catalan law (due to the civil domicile of the parties or by express choice), a company could file a claim for contractual breach (aliud pro alio) seven, eight, or nine years after delivery, whereas in Madrid that action would have prescribed after five years.
Interruption vs. Suspension in Catalan Law
The CCCat is also more sophisticated in managing time:
- Interruption: Any valid extrajudicial claim restarts the 10-year period from zero.
- Suspension: Article 121-15 introduces suspension for force majeure, stopping the clock if the holder of the claim cannot exercise it due to causes beyond their control, with the period resuming (not restarting) when the cause ceases. This was crucial during the COVID-19 lockdowns but also applies to other situations of factual impossibility.
Strategic Insight: For a supplier company based outside Catalonia that sells to a Catalan company, it is vital to include clauses submitting to common law or to non-Catalan jurisdictions to avoid exposure to ten-year liability. Conversely, the Catalan buyer should strive to maintain the application of its own civil jurisdiction.
Technical Evidence: The Expert Report as a Cornerstone
In disputes over latent defects or manufacturing flaws, the judge lacks the technical knowledge to assess whether a shaft failure is due to material fatigue (original defect) or operational overload (misuse). Therefore, the expert report is not just another piece of evidence; it is the key evidence.
Quality Standards: UNE 197001 Standard
An expert report cannot be a mere written opinion. To carry weight in court and withstand cross-examination, it must adhere to recognized quality standards, such as UNE 197001, “General Criteria for the Preparation of Expert Reports and Opinions.”
Traceability
The report must document the chain of custody of the analyzed samples.
Methodology
It must explain not only the conclusion reached but also how it was reached (destructive testing, metallographic analysis, thermography, software log analysis).
Objectivity
The expert must include both data that supports their client and data that does not, under oath to tell the truth (Art. 335 LEC). An overly biased report loses credibility before the judge.
Causation and Preexistence
The greatest evidentiary challenge is not proving that the machine is broken, but proving that the cause of the failure existed in a latent state (“in germ”) at the time of delivery.
- Evidentiary Technique: In cases of corrosion defects, for example, analyses of oxidation depth can date the start of the chemical process before the delivery date. In electronic failures, internal system error logs can show intermittent malfunctions from the first day of operation.
Reversal of the Burden of Proof in the B2B Context
Traditionally, Article 217 of the Civil Procedure Law places the burden of proving the defect on the plaintiff (buyer). However, recent Supreme Court case law, applying the principle of “ease of proof,” has been shifting this burden in cases where there is a significant technical asymmetry.
- Doctrine of Availability: If the seller is the manufacturer and has exclusive control over the production process and technical know-how, they are in the best position to prove that the product left the factory flawless. Courts increasingly require the seller to provide evidence of their quality controls (QC records) to exonerate themselves, rather than forcing the buyer to provide nearly impossible proof of the manufacturing process.
Limitation Clauses and Contractual Risk Management
The freedom of contract (Art. 1255 CC) allows companies to agree on liability regimes different from those established by law, always within certain limits. These clauses constitute the seller’s first line of defense and the buyer’s first obstacle.
Validity of Exculpatory Clauses in B2B
Unlike consumer contracts, where unfair terms are null and void by operation of law, in transactions between businesses, clauses that limit or exclude liability for latent defects are fully valid, provided they are clear and expressly accepted.
Common Typology
Quantitative Limitation
“The seller’s maximum liability is limited to 100% of the product price, excluding lost profits.”
Temporal Limitation
“The warranty period is reduced to 12 months, after which any action expires.”
Limitation of Remedies
“The seller’s sole obligation shall be repair or replacement, with the buyer waiving the right to contract termination.”
The Unbreakable Limit: Fraud
Article 1485 of the Civil Code establishes that the seller is liable for latent defects even if they were unaware of them, “unless otherwise agreed.” However, it adds a critical caveat: any waiver is null if the seller knew of the defects and did not disclose them.
- The Concept of Civil Fraud: Intent to harm is not required; it is enough that the defect was known and consciously concealed. If, during discovery or preliminary proceedings, internal emails from the seller discussing the defect before the sale come to light, any liability limitation clause is voided, opening the door to full compensation for all damages and losses.
Due Diligence and Representations & Warranties (R&W)
In M&A transactions (company sales), the risk of latent defects in the acquired company’s assets is managed through Due Diligence.
- Effect of Due Diligence: If the buyer conducts a thorough audit, they can hardly claim latent defects regarding items that were reviewed. It is presumed that the price already reflected the risks identified.
- Sandbagging: This is the practice of buying while knowing a defect exists in order to claim it later. In Spain, contractual good faith (Arts. 7 and 1258 CC) limits this practice, unlike in Anglo-Saxon jurisdictions where it is sometimes allowed through “Pro-Sandbagging” clauses.
International Perspective: Incoterms and the Vienna Convention
In a global market, many transactions involve companies from different countries. Here, the Spanish Commercial Code often gives way to international regulations.
The 1980 Vienna Convention (CISG)
If the buyer and seller have their establishments in states that are parties to the Convention (such as Spain, France, the U.S., China, Germany), the CISG applies automatically unless expressly excluded in the contract.
- Lack of Conformity (Art. 35 CISG): The CISG does not refer to “latent defects,” but to “lack of conformity.” It is a broader, more functional concept.
- Notice Period (Art. 39 CISG): The buyer must notify within a “reasonable time.” Although flexible, there is an absolute limit of two years from physical delivery. This two-year period acts as a final statute of expiration, overriding national deadlines.
Incoterms 2020 and the Transfer of Risk
It is crucial not to confuse an inherent defect with transport damage. Incoterms define the exact moment when the risk transfers from the seller to the buyer.
- Critical Scenario: In an EXW (Ex Works) sale, the risk passes to the buyer as soon as the goods are made available at the seller’s factory. If the goods arrive damaged from transport, the seller is not liable. The buyer must prove that the damage is an intrinsic manufacturing defect and not a transport-related impact. In CIF or DAP sales, the dynamics change.
Sectoral Strategies and Final Recommendations
Automotive Sector and Fleet Management
Odometer tampering or concealing prior structural accidents are the most frequent cases. Case law (Provincial Court of Zaragoza) has been clear: altering the mileage is not a mere defect; it constitutes an error in consent or even a criminal offense, allowing for the radical nullification of the contract, overriding the short deadlines for latent defects.
Recommendation: Always request the vehicle inspection (ITV) and certified maintenance history before purchase. Include a contract clause in which the seller expressly guarantees the mileage.
Industrial Machinery
The focus should be on the “performance test.”
Recommendation: Do not accept delivery until the machine has operated at full capacity during a trial period (e.g., 48 continuous hours). Link the final payment (often 10–20%) to the signing of the final acceptance certificate without reservations.
Immediate Action Protocol
Industrial claims management allows no room for error. Commercial good faith is important, but legal certainty is non-negotiable.
If you receive a defect claim, do not improvise. Activate this defense protocol:
Strategic Silence
Do not respond in writing admitting errors or offering hasty compensation. An apology email can be used as an acknowledgment of debt and may restart expired deadlines.
Date Audit
Retrieve the signed delivery note. Count the calendar days until the first valid complaint. Have more than 30 days passed? More than 4 days if the defect was visible?
Evidence Preservation
Require the return of the defective sample. Do not accept reports based solely on photos. Your experts need to analyze whether the failure is inherent or due to handling (the client’s fault in selection or use).
Contact Specialists
At GRÀCIACALBET, we combine deep expertise in industrial litigation with agile business management. We understand the difference between a defective screw and one whose claim has expired.
Facing a complex claim? Don’t let deadlines work against you. Contact our team of Industrial and Commercial Law specialists. We will analyze your case through the lens of “Legal Simplicity” to find the strongest and most cost-effective defense for your business.
