You are accused of importing Chinese components that infringe a patent

The case, in five lines

What is brought

The importer's defence against the patent holder: a reply to the warning letter, a protective letter (art. 132 of Law 24/2015, the Spanish Patents Act), objection to destruction and early release against security before Spanish Customs (arts. 23 and 24 of Regulation (EU) 608/2013), a defence with a counterclaim for revocation (arts. 119 and 120) or an action for a declaration of non-infringement (art. 121). And a claim against the Chinese supplier under its warranty against third-party rights (arts. 42 and 43 of the 1980 Vienna Convention).

Before which court

The Sección de lo Mercantil del Tribunal de Instancia (the commercial section of the court of first instance) that has been assigned patent cases (art. 118 of the Patents Act and art. 87(6)(a) of the LOPJ, Spain's Organic Law of the Judiciary); Spanish Customs, for the detention. Against the Chinese supplier, the forum in the contract: the agreed arbitral tribunal, such as CIETAC (China International Economic and Trade Arbitration Commission), or the sección civil del Tribunal de Instancia (the civil section of the court of first instance) if the contract submits to the Spanish courts. In China, a Spanish judgment is recognised and enforced before the Intermediate People's Courts under the 1992 Treaty, and an award made outside China under the New York Convention; an award from an arbitration seated in China is a Chinese award there and does not go through that Convention.

Deadline

Before Spanish Customs, ten working days from notification to object to destruction (art. 23(1) of Regulation 608/2013). In the lawsuit, two months to file the defence and any counterclaim (art. 119). A protective letter remains effective for three months (art. 132). The patent holder's actions are time-barred five years after they could first be brought (art. 78(1)). As regards the supplier, the patent holder's claim must be notified to it within a reasonable time (art. 43 of the Vienna Convention).

Who can bring it

You, as importer and as declarant or holder of the detained goods, against the patent holder bringing the claim. And, as buyer, against the seller named in the contract, whether the factory or a trading company. The customs declaration is lodged by your company or by your customs representative.

Financial risk

The importer is liable for damages even if it knew nothing (art. 72(1)), and compensation may be calculated on its own profits and even on a reasonable share of those from the whole robot (arts. 74 and 75). Staying silent before Spanish Customs allows the goods to be destroyed. If you supplied the drawings, or notify the supplier late, you lose recourse against it (arts. 42(2) and 43). Nobody can promise you the outcome of the lawsuit.

Importing is itself an infringement, and the importer pays even if it did not know

A patent gives its holder the right to prevent any third party, without its consent, from importing the patented product or possessing it in order to offer, sell or use it (art. 59(1)(a) of Law 24/2015, the Spanish Patents Act). Nothing needs to be manufactured in Spain: bringing into the country the gearbox, magnet or cell that reproduces the claims is already an act of infringement. And if there is a Spanish patent for the manufacturing process, which is common with sintered magnets and rare earth oxides, a product made in China using that process is covered as if it had been made here; if the product is also new, it is presumed to have been obtained by the patented process unless the contrary is proved (art. 69).

What nobody tells you is that the importer cannot shelter behind its good faith. Whoever imports without the holder's consent is liable for damages in every case, whether it knew or not (art. 72(1)). The milder rule, under which a party is liable only if it acted knowingly or negligently, and in any event from the warning letter identifying the patent, applies to other acts of exploitation (art. 72(2)): to the integrator or distributor who buys from you in Spain, not to you. That is why the holder usually goes after the importer first, and why your customer will ask you to cover it.

Nor are you protected by what happens in China. Patents are territorial: what counts is the Spanish patent or the European patent validated in Spain, which has the effect of a national patent here (art. 153), not your supplier's Chinese patent. Nor does the fact that the holder sells the same product in China allow you to import it, because exhaustion only operates when the product has been put on the market in the European Economic Area by the holder or with its consent (art. 61(2)). And if you sell the component separately to whoever assembles it, there may be indirect infringement: supplying means relating to an essential element of the invention, knowing, or it being obvious, that they are intended to put it into effect (art. 60(1)), unless it is a staple commercial product and you do not induce infringement (art. 60(2)).

The patent holder's letter: what to answer, what to sign and what not to

A warning letter is not a lawsuit, but it changes everything: any customer of yours who receives one can no longer claim it did not know (art. 72(2)), and it is usually the step before an application for interim measures. Before answering, the patent is checked: who the holder is, whether it is still in force, what claims it has today, its priority date and, if it is European, whether it was validated in Spain with its Spanish translation (art. 155(1)). Then, with our engineering experts, your component is compared, element by element, with the main claim. The reply is written with that comparison in hand, admitting nothing and leaving nothing that is asked unanswered.

If the risk is real, a negotiated way out is usually best: a licence, or a settlement that settles what has already been imported and allows the stock to be sold off. What nobody tells you is art. 78(2): if the importer has adequately compensated the holder, the holder can no longer sue those who later exploit the goods the importer put on the market. A well-drafted settlement thus protects your entire chain of customers; one that covers only your company leaves your integrators exposed and you facing their claims. In addition, any compensation already received by the holder for the same item from others in the chain is deducted from what can be claimed from the importer (art. 77).

If the holder threatens measures without hearing you, you can get in first with a protective letter before the competent section: interim measures proceedings are opened, the holder is notified and, if it applies for measures within the following three months, the judge may hear you before deciding, although the judge can still grant them without a hearing (art. 132). If you are confident you do not infringe, an action for a declaration of non-infringement is available, so that the judge declares that your component does not infringe, after formally requiring the holder to state its position and waiting a month without a reply or with one you do not accept (art. 121); it is not available once you have been sued for infringement. And before suing you, the holder must also first attempt negotiation (Ley Orgánica 1/2025, Organic Law 1/2025, arts. 3(1) and 5), although not in order to seek interim measures before the claim is filed (art. 5(3)).

If Spanish Customs detains the components: ten working days

Regulation (EU) 608/2013 does not only allow customs to detain trade mark counterfeits: it also covers goods suspected of infringing patents, utility models and semiconductor topographies (art. 2(1)), which reaches chips and boards. If the holder has previously filed an application for action, Spanish Customs suspends release or detains the goods and notifies you, as declarant or holder of the goods, within one working day (art. 17). If it detains them on its own initiative without a prior application, the holder has four working days to file one and, if it does not, the goods are released (arts. 5(3) and 18(4)).

From notification you have ten working days to object in writing to destruction. If you stay silent, customs may presume that you consent, and the parts may be destroyed without anyone having decided whether they infringed (art. 23(1)). If you object, the holder must, within ten working days of being notified of the detention, extendable by ten more on a justified request, initiate proceedings to determine whether there is an infringement; if it does not, customs grants release (art. 23(3) to (5)). The fast-track procedure for small consignments does not apply to patents, only to counterfeiting and piracy (art. 26(1)(a)).

What nobody tells you is that with patents there is a way out that does not exist for trade marks: early release. Once proceedings have been initiated, you may ask customs to release the goods against sufficient security to protect the holder, provided that the court has not granted interim measures and the customs formalities have been completed (art. 24). And if the parts turn out not to infringe, the holder is liable for the damage the detention caused you (art. 28). The customs declaration stays with your company or your customs representative; we prepare and file the objection and the release request under your authorisation. Where the problem is a trade mark rather than a patent, it is explained in "Your goods detained at Spanish customs as suspected counterfeits".

How to defend the lawsuit: non-infringement, invalidity and prior use

The infringement claim goes to the Sección de lo Mercantil del Tribunal de Instancia (the commercial section of the court of first instance) with jurisdiction over patents, in the city where the Tribunal Superior de Justicia (the regional High Court of Justice) sits, wherever the Consejo General del Poder Judicial (Spain's General Council of the Judiciary) has assigned it those cases (art. 118 of the Patents Act, which still refers to the Commercial Court judge, and art. 87 of the LOPJ): the one for the defendant's domicile or, at the holder's choice, for the place where the infringement occurred or had its effects. Since 31 December 2025 there have been no Commercial Courts as such. And Spain is not part of the Unified Patent Court: a European patent validated here is litigated here, and the unitary patent does not cover Spain, whose challenges to that system were dismissed by the Court of Justice of the European Union (Cases C-146/13 and C-147/13, of 5 May 2015).

There are two months to file the defence and, where appropriate, a counterclaim, and expert reports are filed with the defence unless that is shown to be impossible (art. 119). The defence is built on three levels. First, non-infringement: your component does not reproduce every element of the claim. Second, total or partial invalidity of the patent, by counterclaim or by way of defence (art. 120(1)); if raised as a defence, the holder has eight days to ask for it to be treated as a counterclaim (art. 120(2)), and it may limit its claims to save the patent (art. 120(3)). Third, the statutory limits: good-faith prior use in Spain before the priority date, which also bars interim measures (arts. 63 and 128(3)), or acts for experimental purposes relating to the subject matter of the invention (art. 61(1)(b)).

Patent lawsuits are won with experts. The report that reaches the trial is signed by an expert holding an official qualification (art. 340 of the Ley de Enjuiciamiento Civil, Spain's Civil Procedure Act), but its groundwork is laid earlier and far away: we work with partners with offices in China and with engineering experts in Spain and China who examine the component and its specifications before shipment, take samples and run tests on arrival and, if the supplier cooperates, document its manufacturing process at the plant. That last point is decisive against a process patent, because the presumption in art. 69(2) can only be rebutted by proving how the product was made, with protection for manufacturing secrets (art. 69(3)). A commercial inspection at the factory is a private activity; formal judicial evidence-taking in China for Spanish proceedings goes through the treaties (art. 12 of State Council Decree 801, in force since 1 May 2025). If the validity of the patent is challenged and the parties' reports conflict, the judge may ask the Oficina Española de Patentes y Marcas (Spanish Patent and Trade Mark Office) for one (art. 120(7)).

What it can cost you: injunction, seizure and damages

The holder may seek an injunction, damages, seizure of what was imported and of the means used exclusively to produce it, transfer of ownership with its value set against the damages, its alteration or destruction where indispensable and, exceptionally, publication of the judgment (art. 71(1)). The injunction and the measures to prevent the infringement from continuing, such as alteration or destruction, may also be directed against intermediaries whose services are used, such as the freight forwarder, the warehouse or the platform, even though they do not infringe (art. 71(2)). The actions are time-barred five years after they could first be brought (art. 78(1)): it is not only the last container that is at stake.

Damages cover the loss suffered, the profit lost and the holder's investigation costs, and the holder chooses how to calculate them: by the profits it would have made without your competition, by the profits you made, or by a lump-sum hypothetical royalty, with non-material damage even if no economic loss is proved (art. 74(1) and (2)). What nobody tells you: if the component is the commercially essential part of the robot you sell, the profits on the whole robot may be counted, in the proportion the court considers reasonable (art. 75). And if you are ordered to stop, the court also sets a coercive penalty for each day that passes until you actually stop (art. 74(4)).

Before judgment, the holder may seek interim measures: an injunction, detention and deposit of the goods, security for the damages and any appropriate entries in the registers (art. 128(1)). The applicant provides security to answer for any damage caused, within the period set by the judge, never less than five working days, and if it does not, it is deemed to have waived the measures (art. 129(1)). The judge may set an amount of security that you can lodge at any time to replace measures that restrict your business (art. 129(2)), which may take the form of a bank guarantee but never a personal guarantee (art. 129(4)). The holder may also ask for urgent fact-finding measures at your premises if infringement is presumable and there is no other way to verify it (art. 123); if it does not sue within thirty working days of receiving the certified record, they lapse (art. 125(2)).

Making the Chinese supplier pay: art. 42 and the missing clause

Between your company and a seller established in China, the 1980 Vienna Convention on Contracts for the International Sale of Goods (CISG) applies unless the contract excludes it (arts. 1(1)(a) and 6). Its art. 42 requires the seller to deliver goods free from third-party rights or claims based on industrial property of which it knew or could not have been unaware when contracting, under the law of the State where the goods were expected at the time of contracting to be resold or used and, otherwise, under the law of the State where the buyer has its place of business. If it breaches that warranty, you have the buyer's remedies, among them damages for the loss the supplier foresaw or ought to have foreseen when contracting (art. 74).

What nobody tells you is that two doors close this route. First, the seller is not liable if you knew or could not have been unaware of the patent when contracting, nor where the infringement results from its having complied with your drawings, formulas or specifications (art. 42(2)). In OEM manufacturing to the customer's drawings, the patent risk is usually yours. Second, you lose the right if you do not notify the supplier of the third party's claim, specifying its nature, within a reasonable time after you became or ought to have become aware of it (art. 43(1)), unless the supplier already knew of it (art. 43(2)). The holder's letter or the customs notification is passed on to it at once, in writing and identifying the patent; our partners with offices in China follow up the factory's response on the ground. If the parts also fail on grade or tolerances, that is covered in "Your Chinese supplier delivers magnets or parts that are not as agreed".

Where the claim is brought is set by the contract: the agreed arbitration, for example before CIETAC; the Spanish courts if there is a jurisdiction clause, valid whatever the supplier's domicile (art. 25 of the Brussels I bis Regulation), after attempting the negotiation required by Organic Law 1/2025; without a clause, they have jurisdiction if the obligation was or should have been performed in Spain (art. 22 quinquies(a) of the LOPJ). Whatever you win is enforced where the supplier has assets: a Spanish judgment, in China, under the 1992 Spain-China Treaty before the Intermediate People's Courts and without review of the merits (arts. 17 to 23); an award made outside China, under the New York Convention; one from an arbitration seated in China is a Chinese award there and does not go through that Convention. If the contract chooses no law, a Spanish court will apply Chinese law, which allows four years to sue or commence arbitration over an international sale (art. 594 of China's Civil Code); under Spanish law, five (art. 1964(2) of the Spanish Civil Code). How to choose the forum is explained in "You want to sue your Chinese supplier: arbitration or the courts?".

How we run the case, step by step

1. 1

   Pin down the deadlines on day one

   From the holder's letter or the customs notification, we calculate the deadlines already running: ten working days to object to destruction, two months to file a defence if a claim has been served, and the reasonable time to notify the supplier. None is left until after the merits have been studied.

2. 2

   Review the patent and the component with our engineering experts

   We check ownership, whether the patent is in force, its claims, its priority date and its validation in Spain. Our engineering experts in Spain and China compare the component with each element of the claim, using samples, technical data sheets and, if the supplier cooperates, a visit to the plant to document the manufacturing process.

3. 3

   Protect the goods

   An objection to destruction and, once proceedings have begun, a request for early release against security (arts. 23 and 24 of Regulation 608/2013). If measures without a hearing are feared, a protective letter (art. 132 of the Patents Act). The customs declaration remains with your company or your customs representative.

4. 4

   Notify the Chinese supplier

   A written notice identifying the patent and the nature of the claim (art. 43 of the Vienna Convention), asking for its position on infringement, documentation of its process and its undertaking to cover you. Our partners with offices in China follow up the response at the factory.

5. 5

   Negotiate with the patent holder

   A reasoned reply to the letter and, if the risk is real, a licence or settlement that settles what was imported and covers your customers (art. 78(2) of the Patents Act), framed as the negotiation attempt required by Organic Law 1/2025, bearing in mind that the request interrupts limitation of the actions, including the holder's actions against you (art. 7(1)).

6. 6

   Litigate if there is no settlement and shield future orders

   A defence with a counterclaim for revocation and expert reports (arts. 119 and 120), or an action for a declaration of non-infringement (art. 121); a claim against the supplier in the contractual forum; and, going forward, a warranty and indemnity clause against third-party patents, with inspection at origin by our network in China.

The law that applies

• Arts. 59, 60, 61 y 69 de la Ley 24/2015, de Patentes. A patent allows its holder to prevent a third party without consent from importing the patented product or possessing it in order to offer, sell or use it, and from supplying means relating to an essential element of the invention to someone not entitled to exploit it. Exhaustion only operates through marketing in the European Economic Area. Where there is a process patent, a product brought into Spain is covered and, if it is new, is presumed to have been obtained by that process. BOE-A-2015-8328
• Arts. 71, 72, 74, 75 y 78 de la Ley 24/2015, de Patentes. Actions for an injunction, damages, seizure and destruction; the injunction and the measures to prevent the infringement from continuing, also against intermediaries. Whoever imports without consent is liable for damages in every case; others, if they acted knowingly or negligently, and always from the warning. Damages are calculated by the holder's or the infringer's profits or by a hypothetical royalty, with a daily coercive penalty. Actions are time-barred after five years, and an importer that has already paid compensation frees those who later exploit what it put on the market. BOE-A-2015-8328
• Arts. 119, 120, 121, 128, 129 y 132 de la Ley 24/2015, de Patentes. Two months to file the defence and counterclaim, with expert reports. The defendant may plead invalidity of the patent by counterclaim or by way of defence, and an action for a declaration of non-infringement is available after a prior formal demand. Interim measures with security from the applicant and substitute security from the defendant, not available against a prior user. Protective letter against measures without a hearing, effective for three months. BOE-A-2015-8328
• Arts. 2, 17, 23, 24, 26 y 28 del Reglamento (UE) 608/2013. Customs may detain goods suspected of infringing patents and semiconductor topographies. The declarant has ten working days to object to destruction and silence may be taken as consent; the holder must initiate proceedings within ten working days, extendable by ten more. For patents, early release against security is available and the small consignments procedure does not apply. The holder is liable if the goods did not infringe. 32013R0608
• Arts. 42 y 43 de la Convención de Viena de 1980. The seller must deliver goods free from third-party industrial property rights of which it knew or could not have been unaware when contracting, under the law of the State of intended resale or of the buyer. It is not liable if the buyer knew of them or if it followed the buyer's drawings or specifications. The buyer loses the right if it does not notify the third party's claim within a reasonable time, unless the seller knew of it. BOE-A-1991-2552
• Art. 87 de la LO 6/1985, del Poder Judicial. Following Organic Law 1/2025, the Tribunal de Instancia (court of first instance) in each provincial capital has a Sección de lo Mercantil (commercial section) that hears civil intellectual and industrial property matters; actions on EU trade marks belong exclusively to the Alicante section. BOE-A-1985-12666
• Arts. 3, 5 y 7 de la Ley Orgánica 1/2025. Before bringing a civil claim, an appropriate means of dispute resolution must be attempted, including in cross-border disputes. It is not required for interim measures before the claim, preliminary inquiries or enforcement claims. The request interrupts limitation or suspends time-bars. BOE-A-2025-76

Each article checked against the consolidated text published in the BOE (the Spanish official gazette).

Frequently asked questions