German Contract Law
Sources and Structure
German contract law (Vertragsrecht) is codified in Book 2 of the Bürgerliches Gesetzbuch (BGB) — the German Civil Code — which entered into force on 1 January 1900 and was fundamentally modernised by the 2002 reform of the law of obligations (Schuldrechtsmodernisierung). The BGB’s structure follows the Pandectist tradition, moving from general to particular: Book 1 (General Part, §§ 1-240) contains provisions on legal persons, declarations of will, and contracts generally; Book 2 (Law of Obligations, §§ 241-853) contains the general law of obligations followed by specific contractual types (Kaufvertrag, Mietvertrag, Werkvertrag, etc.); Book 3 (Property Law, §§ 854-1296) governs the transfer of ownership. The 2002 reform transposed several EU consumer protection directives into the BGB, restructured the law of prescription (Verjährung), and recast the law of non-performance.
Freedom of Contract and Private Autonomy
German contract law is founded on the principle of private autonomy (Privatautonomie), encompassing the freedom to contract (Abschlussfreiheit) and the freedom to determine the content of the contract (Gestaltungsfreiheit). Article 2(1) of the Grundgesetz (Basic Law) protects private autonomy as a constitutional right. This freedom is limited by mandatory statutory provisions, especially those protecting weaker parties: § 138 BGB voids legal transactions contrary to good morals (gute Sitten), and § 138(2) specifically voids exploitative transactions (Wucher) where a party exploits another’s predicament, inexperience, or lack of judgment to obtain disproportionate benefits. The Allgemeine Geschäftsbedingungen (standard business terms) under §§ 305-310 BGB are subject to substantive fairness control.
Formation of Contract
Contract formation requires at least two concordant declarations of will (Willenserklärungen): offer (Angebot or Antrag) and acceptance (Annahme), regulated by §§ 145-157 BGB. An offer is a binding declaration requiring the definite expression of the essential contractual terms (essentialia negotii). Under § 145 BGB, an offer is binding on the offeror unless the offeror has excluded binding effect. Acceptance must be unconditional and correspond to the offer; a qualified acceptance is treated as a new offer under § 150(2) BGB.
Declarations of will are effective upon receipt (Zugang) under § 130 BGB — the receipt theory (Zugangstheorie). A declaration is received when it enters the other party’s sphere of control such that the addressee can, under normal circumstances, take cognisance of it. The BGB does not adopt the common law’s postal rule; risk lies with the declarant until receipt. The offeror may fix a period for acceptance (§ 148 BGB); otherwise, acceptance must occur within a reasonable time (§ 147 BGB). Silence does not generally constitute acceptance, though commercial confirmation letters (kaufmännisches Bestätigungsschreiben) are an exception recognised by commercial custom.
Interpretation
The BGB provides two interpretation rules. § 133 BGB requires that the actual intention (wirklicher Wille) be ascertained in interpreting a declaration of will, going beyond the literal meaning. § 157 BGB requires that contracts be interpreted according to good faith (Treu und Glauben) with regard to customary practice (Verkehrssitte). The objective recipient perspective (objektiver Empfängerhorizont) — what a reasonable addressee would understand — governs, consistent with the protection of reasonable expectations.
Mistake and Avoidance
The BGB distinguishes several categories of mistake (Irrtum) that entitle a party to avoid (anfechten) the contract under §§ 119-124 BGB. § 119(1) covers content mistake (Inhaltsirrtum) — the declarant does not know what they are declaring — and declaration mistake (Erklärungsirrtum) — the declarant does not intend to declare what the declaration objectively means. § 119(2) covers mistake as to essential characteristics of the person or thing (Eigenschaftsirrtum), provided the characteristic is regarded as essential in business dealings. Avoidance is by declaration to the other party (§ 143 BGB) and must occur without culpable delay (unverzüglich) after discovery (§ 121 BGB) and within the statutory period.
The avoiding party is liable for reliance damages under § 122 BGB — the negative interest (Vertrauensschaden) — limited to the amount the other party would have had if the declaration had been valid from the outset. This reflects the balance between protecting the mistaken party and compensating the other party’s reliance. Fraudulent deception (arglistige Täuschung) and unlawful threats (widerrechtliche Drohung) under § 123 BGB give a stronger right to avoidance without the § 122 damages liability, and the avoidance period is one year.
The 2002 Reform of the Law of Obligations
The Schuldrechtsmodernisierungsgesetz, effective 1 January 2002, was the most comprehensive reform of the BGB since its enactment. The reform transposed the EU Consumer Sales Directive (1999/44/EC), the Unfair Contract Terms Directive (93/13/EEC), and other consumer protection directives into the BGB, replacing the former separate consumer protection statutes. The limitation period (Verjährung) was standardised: the regular period is three years (§ 195 BGB), running from the end of the year in which the claim arose and the creditor obtained knowledge or ought to have obtained knowledge (§ 199 BGB). The previously fragmented law of non-performance was restructured around the central concept of breach of duty (Pflichtverletzung) under § 280 BGB, unifying the former categories of impossibility, delay, and positive malperformance.
Performance and Non-Performance
The obligee’s right to claim performance (Erfüllungsanspruch) is primary. Specific performance is the principal remedy — the creditor is entitled to actual performance, not merely damages. The law of non-performance is structured around the categories of impossibility (Unmöglichkeit), delay (Verzug), and defective performance (Schlechtleistung). §§ 275-292 BGB govern impossibility: if performance is impossible for the debtor, the claim for performance is excluded (§ 275(1)), but the creditor may claim damages in lieu (§ 283) or, if the debtor caused the impossibility, damages for non-performance. §§ 280-286 BGB govern damages: § 280(1) establishes liability for damages arising from breach of duty unless the debtor proves absence of fault (the burden of proof shifted by the reform).
Damages and Restitution
German damages law distinguishes between the positive interest (Erfüllungsinteresse or expectation interest) — placing the creditor in the position as if the contract had been properly performed — and the negative interest (Vertrauensinteresse or reliance interest). The fundamental principle is natural restitution (Naturalrestitution) under § 249 BGB: the injured party is entitled to be placed in the position that would exist if the damaging event had not occurred. Where natural restitution is not possible or is insufficient, monetary compensation (Geldentschädigung) under § 251 BGB applies. Damages for delay (Verzugszinsen) are regulated by § 288 BGB, with interest at 5 percentage points above the base rate for consumer transactions and 9 percentage points for commercial transactions.
Impossibility and Frustration
German law distinguishes between objective impossibility (unmöglich for everyone, § 275(1)), practical impossibility (factual impossibility, § 275(2) — Leistungsverweigerungsrecht where performance requires disproportionate effort), and personal impossibility (§ 275(3) — Leistungsverweigerungsrecht where performance cannot reasonably be required in person). The doctrine of the foundation of the transaction (Geschäftsgrundlage) under § 313 BGB, codifying the judge-made law developed after World War I, provides for adaptation or termination of the contract when circumstances have fundamentally changed since conclusion and the parties would not have contracted (or would have contracted on different terms) had they foreseen the change. This is the civil law counterpart to frustration of purpose.