Contract law
Formation
Capacity Offer and acceptance Meeting of the minds2 Abstraction principle4,5 Posting rule1 Mirror image rule Invitation to treat Firm offer Consideration1,4 Implication-in-fact Collateral contract
Defences
Misrepresentation Mistake Threats and unequal bargaining power Illegality and public policy Unconscionability Culpa in contrahendo2 Force majeure Frustration of purpose Impossibility Impracticability Hardship Set-off Illusory promise1 Statute of frauds1 Non est factum1 Unclean hands1 Accord and satisfaction1 Exculpatory clause
Interpretation
Parol evidence3 Contract of adhesion Integration clause Contra proferentem UNIDROIT Principles of International Commercial Contracts
Dispute resolution
Choice of law clause Forum selection clause Hague Choice of Court Convention Arbitration New York Convention UNCITRAL Model Law on International Commercial Arbitration Mediation Singapore Mediation Convention Enforcement of foreign judgments Hague Judgments Convention
Rights of third parties
Privity of contract1 Assignment Delegation Novation Third-party beneficiary
Breach of contract
Anticipatory repudiation Cover Exclusion clause Efficient breach Deviation Fundamental breach
Remedies
Specific performance3 Money damages Liquidated, stipulated, or penal damages3 Rescission
Quasi-contractual obligations
Promissory estoppel1 Quantum meruit1 Unjust enrichment Restitution Negotiorum gestio2
Duties of parties
Duty of honest contractual performance (or doctrine of abuse of rights)6 Duty of good faith (also implied covenant of good faith and fair dealing or duty to negotiate in good faith)7 Contract A and Contract B6
Related areas of law
Conflict of laws Commercial law
By jurisdiction
Australia Canada China (mainland) Ireland India Saudi Arabia United Kingdom England and Wales Scotland United States
Other law areas
Tort law Property law Wills, trusts, and estates Criminal law Evidence
Notes
1 Specific to common law jurisdictions 2 Specific to civil and mixed law jurisdictions 3 Historically restricted in common law jurisdictions but generally accepted elsewhere; availability varies between contemporary common law jurisdictions 4 Specific to the German Bürgerliches Gesetzbuch and other civil codes based on the pandectist tradition 5 Explicitly rejected by the UNIDROIT Principles of International Commercial Contracts 6 Specific to Canadian contract law both in Québec and in the country's common law provinces 7 Specific to civil law jurisdictions, the American Uniform Commercial Code, and Canadian jurisprudence in both Québec and the common law provinces pertaining to contractual and pre-contractual negotiation
v t e

A firm offer is an offer that will remain open for a certain period or until a certain time or occurrence of a certain event, during which it is incapable of being revoked.^[1] As a general rule, all offers are revocable at any time prior to acceptance, even those offers that purport to be irrevocable on their face.

In the United States, an exception is the merchant firm offer rule set out in Uniform Commercial Code - § 2-205, which states that an offer is firm and irrevocable if it is an offer to buy or sell goods made by a merchant and it is in writing and signed by the offeror.^[2] Such an offer is irrevocable even in the absence of consideration. If no time is stated, it is irrevocable for a reasonable time, but in no event may a period of irrevocability exceed three months. Any such term of assurance in a form supplied by the offeree must be separately signed by the offeror.

However, even when the period of irrevocability expires, the offer may still remain open until revoked or rejected according to the general rules regarding termination of an offer.

If the offeree rejects, fails to accept the terms of the offer, fixed or otherwise, or makes a counter-offer, then the original offer is terminated.