--- title: "AI agent liability: who pays when an agent buys the wrong thing?" url: https://knowyouragent.ch/en/knowledge/ai-agent-liability lang: en updated: 2026-10-13 license: © Innopulse Consulting GmbH --- # AI agent liability: who pays when an agent buys the wrong thing? An AI agent is not a legal person. Its declarations are generally attributed to whoever deploys it. Whether that person ends up paying depends on what the agent was allowed to do and whether this can be proven. [Leutrim Miftaraj](https://knowyouragent.ch/en/about/leutrim-miftaraj), Founder, Innopulse Consulting GmbH Published 13 October 2026 ## Key points - An AI agent is not a legal person; its declarations are generally attributed to whoever deploys it. - Outside the limits granted, a transaction generally binds only after ratification. - Switzerland, Germany and Austria follow similar patterns, with differences in detail. - Verifiable evidence defuses disputes because it proves the decisive facts. ## The principle: attribution to whoever deploys the agent An AI agent makes no declaration of intent of its own. A widely held view in all three countries attributes automatically generated declarations to whoever operates the system; German legal writing calls them computer declarations. Anyone who lets an agent order on their behalf must therefore, as a rule, accept its declarations as their own. It is also debated whether the rules of agency apply by analogy. In that case, the [authority to act](https://knowyouragent.ch/en/knowledge/glossary/authority-to-act) becomes decisive, meaning the limits the [principal](https://knowyouragent.ch/en/knowledge/glossary/principal) has set. In practice, both paths lead to the same question: was the action within what the agent was deployed for, and can anyone prove it? ## Switzerland: Code of Obligations A contract is concluded through mutual expressions of intent (Article 1 of the Code of Obligations). Agency is governed by Articles 32 et seq. If the authorization was communicated to a third party, its scope toward that party follows the communication (Article 33 paragraph 3). A transaction without authorization binds the principal only if ratified (Article 38); otherwise the unauthorized agent is liable under Article 39. For mistakes, the rules on error may apply (Articles 23 et seq.). Breach of contract falls under Article 97 and auxiliary persons under Article 101; whether that provision applies to software is assessed differently in legal writing. Outside contract, Article 41 remains, and for defective products the Product Liability Act. ## Germany: Civil Code (BGB) Agency is governed by Sections 164 et seq. BGB. A contract concluded without authority remains provisionally ineffective until the principal ratifies it (Section 177 BGB). The agent is liable under Section 179 BGB unless it proves its authority. Case law also recognizes apparent authority and authority by acquiescence when the principal has created the appearance of authority in an attributable way. If a wrong declaration results from an error in processing, rescission for mistake may be possible under certain conditions (Section 119 BGB), combined with compensation for reliance damage (Section 122 BGB). Vicarious agents are covered by Section 278 BGB, liability in tort by Section 823 BGB. ## Austria: Civil Code (ABGB) In Austria, Sections 1002 et seq. ABGB govern the contract of authorization. If the agent exceeds its authority, the principal is bound only insofar as it ratifies the transaction (Section 1016 ABGB). Whoever acts without sufficient authority is liable to the third party (Section 1019 ABGB). Here too, case law protects the reliance of third parties when the principal caused the appearance of authority. Mistakes fall under Section 871 ABGB and vicarious agents under Section 1313a ABGB. How these rules apply to AI agents is not yet fully settled in any of the three countries. The basic patterns are similar, however: attribution, limits, ratification and protection of reliance. ## One case in three variants A customer instructs her agent to book a hotel room for up to CHF 200 per night. **Variant A:** the agent books for CHF 180. The action is within the limits, the contract binds, and there is hardly any dispute. **Variant B:** the agent books a suite for CHF 900. If the hotel did not know the limit, the outcome depends on how the declaration is attributed and what appearance the customer created. If the hotel knew the limit, for example because the mandate was presented, there are strong arguments that it cannot rely on the booking. **Variant C:** a hidden instruction on a website makes the agent book the wrong hotel. Besides attribution and mistake, this raises the question of claims against the provider. The new EU Directive (EU) 2024/2853 expressly brings software within product liability; it must be transposed by 9 December 2026. ## What takes the heat out of liability Most disputes turn not on questions of law but on facts: what was allowed, what was decided, what happened? Whoever can answer these questions with evidence has a clear advantage. - A [mandate](https://knowyouragent.ch/en/knowledge/glossary/agent-mandate) with limits that the agent presents to merchants makes the limits visible to both sides. - A [decision](https://knowyouragent.ch/en/knowledge/glossary/decision-token) before execution records that the specific action was checked. - An [execution receipt](https://knowyouragent.ch/en/knowledge/glossary/execution-receipt) shows what actually happened, and a [timestamp](https://knowyouragent.ch/en/knowledge/glossary/rfc-3161-timestamp) shows when. - Terms and conditions can define how orders by agents are handled and which evidence is required. ## The role of KYA KYA answers no questions of law. It does make the relevant facts verifiable: whether a mandate was valid at the time of the action, whether the action was within its scope, whether it had been revoked and whether execution matched the decision. The result is a certificate that each side can recompute independently. Whether a court follows this evidence is a matter of its free assessment of evidence. Independently verifiable evidence is, however, considerably stronger than a log entry in one's own system. [Verify evidence now](https://knowyouragent.ch/en/verify). ## Frequently asked questions ### Is the user liable if their AI agent buys the wrong thing? As a rule, the agent's declarations are attributed to whoever deploys it. If the purchase was outside the limits granted and the merchant knew those limits, the outcome may differ. The circumstances of the individual case are decisive. ### Can a merchant refuse a purchase made by an agent? Yes. A merchant decides for itself with whom it concludes contracts. It can make orders by agents subject to conditions, such as verifiable proof of authority. ### Is the provider of the AI model liable? That depends on the contract, the cause of the error and the applicable law. In the EU, the new product liability directive expressly covers software; it applies to products placed on the market after 9 December 2026. ### How do I prove that my agent exceeded its limits? With the mandate that records the limits and the receipt of the actual action. Together, they show the deviation. A KYA certificate makes this recomputable for third parties. General information, not legal advice. The statutes and the circumstances of each case are decisive. ## Sources - Obligationenrecht (OR), Art. 32–40: [https://www.fedlex.admin.ch/eli/cc/27/317_321_377/de#art_32](https://www.fedlex.admin.ch/eli/cc/27/317_321_377/de#art_32) - Bürgerliches Gesetzbuch (BGB), §§ 164–181: [https://www.gesetze-im-internet.de/bgb/__164.html](https://www.gesetze-im-internet.de/bgb/__164.html) - Allgemeines bürgerliches Gesetzbuch (ABGB), §§ 1002 ff.: [https://www.ris.bka.gv.at/NormDokument.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10001622&Paragraf=1002](https://www.ris.bka.gv.at/NormDokument.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10001622&Paragraf=1002) - Richtlinie (EU) 2024/2853 über die Haftung für fehlerhafte Produkte: [https://eur-lex.europa.eu/eli/dir/2024/2853/oj](https://eur-lex.europa.eu/eli/dir/2024/2853/oj) --- Quelle: https://knowyouragent.ch/en/knowledge/ai-agent-liability · KYA – Know Your Agent