The principles of contract law come down to five things a court looks for before it will enforce a deal: both sides agreed to the same terms, each side gave up something of value, both parties had the legal capacity to agree, the purpose was lawful, and the terms were definite enough to apply. If any one of these is missing, there may be no contract to enforce. If all five are present, the agreement can be enforced, and a party who breaks it generally owes money damages or, in a narrow set of cases, can be ordered to perform.
Several other doctrines shape how these elements play out: the statute of frauds decides which contracts need to be in writing, defenses like duress and fraud can undo a signed deal, and the remedies available after a breach depend on what was actually lost.
What Makes an Offer and Acceptance Count
A contract begins with one party making an offer and another accepting it. Courts don’t try to read minds. They look at what you said, what you wrote, and what a reasonable person in the other party’s position would have understood.1H2O. Restatement (Second) of Contracts 24 – Offer Defined An offer has to be definite enough that saying yes would close the deal rather than open more negotiations.2H2O. Restatement (Second) of Contracts 22
Acceptance has to match the offer exactly. Change the price, add a condition, swap out a deadline, and you haven’t accepted anything. Under the mirror image rule, that modified response kills the original offer and creates a counter-offer the first party can accept or reject. Until both sides agree on identical terms, nobody is bound.
When Acceptance Takes Effect
Timing matters more than people expect. Under the common-law mailbox rule, an acceptance is effective the moment the accepting party sends it, not when the other side receives it. If you mail a signed acceptance on Monday and the offeror tries to revoke on Tuesday before the letter arrives, you still have a deal. The parties can override this by writing into the offer that acceptance isn’t effective until received.
Electronic Signatures and Online Agreements
Federal law treats electronic signatures as legally equivalent to pen on paper. The Electronic Signatures in Global and National Commerce Act defines an electronic signature as any electronic sound, symbol, or process attached to a record and adopted with the intent to sign it. Clicking “I agree,” typing your name into a signature field, or using a digital signing platform all qualify. The key is intent: you have to be adopting that action as your signature, not just clicking through a page. When electronic records replace paper disclosures, consumers must receive clear notice of their right to request paper copies and withdraw consent.3Federal Deposit Insurance Corporation. X-3 The Electronic Signatures in Global and National Commerce Act (E-Sign Act)
Consideration: What Each Side Must Give Up
A promise alone isn’t enough to create an enforceable contract. Each side has to give something up or take on an obligation in exchange for what the other side promises.4Open Casebook. Restatement (Second) of Contracts 71 – Requirement of Exchange This bargained-for exchange is what separates a binding contract from a gift. A promise to hand someone a car for free isn’t enforceable because the recipient hasn’t given or promised anything in return.
Courts almost never evaluate whether the exchange was fair in dollar terms. You can trade a vintage car for a dollar and have perfectly valid consideration, because the law cares that the parties bargained, not that they struck an objectively equal deal. Even a promise to stop doing something you have a legal right to do can count. The real failure point is when one side provides nothing at all.
When Reliance Replaces Consideration
Sometimes a promise that lacks formal consideration is still enforceable. Under the doctrine of promissory estoppel, a court can enforce a promise when the person who made it should have expected the other side to act on it, the other side did act on it, and letting the promisor walk away would be unjust.5H2O. Restatement Second of Contracts 90 – Promissory Estoppel The classic example: an employer promises a prospective hire a position, the person quits their old job and relocates, and the employer revokes the offer. No formal contract exists, but the reliance was real and foreseeable. Courts have flexibility to limit the remedy to whatever justice requires, sometimes covering only the reliance costs rather than the full value of the broken promise.
Who Can Legally Enter a Contract
Even when offer, acceptance, and consideration all check out, a contract can still be voided if one party lacked the legal ability to enter into it. Capacity issues come up most often with minors and people suffering from mental impairment.
Minors
In nearly every state, anyone under 18 can enter a contract but also has the right to void it. This right of disaffirmance belongs exclusively to the minor; the adult on the other side stays bound unless the minor walks away. A minor can cancel the deal at any time before turning 18 or within a reasonable period afterward, and must cancel the entire agreement rather than keeping the favorable parts. On cancellation, the minor can recover anything transferred as part of the deal.
The major exception involves necessities like food, shelter, clothing, and medical care. A minor who cancels a contract for necessities will still owe the reasonable value of what they received. Otherwise minors could use their special status to get essential goods and services for free.
Mental Incapacity
A person who lacks the mental ability to understand the nature and consequences of a contract can void it. Unlike a minor’s blanket right to cancel, mental incapacity involves a factual determination about whether the person actually comprehended what they were agreeing to. If the incapacitated person later regains capacity, they can choose to ratify the contract and make it binding. If a court has already appointed a legal guardian, contracts signed by the incapacitated person without the guardian’s involvement are void from the start.
Lawful Purpose and Fair Terms
A contract that calls for something illegal is void and was never enforceable to begin with. Courts will not step in to settle a dispute over a deal involving criminal activity, unlicensed professional services, or any other purpose that violates the law. Because these agreements are treated as if they never existed, neither side can recover damages for a breach.
The analysis gets more nuanced when the contract isn’t outright illegal but conflicts with public policy. Courts weigh the parties’ reasonable expectations and any financial loss from refusing to enforce the deal against the strength of the policy concern, how deliberate the misconduct was, and how directly the problematic term connects to the policy violation.6H2O. Restatement Second of Contracts 1-2, 178 A restrictive covenant in a business sale might be enforceable if it’s narrow in scope, but the same clause written so broadly that it prevents someone from earning a living anywhere could fail the public policy test.
Unconscionability
Courts can also refuse to enforce terms that are grossly unfair, even when nobody technically broke the law. Unconscionability has two dimensions. Procedural unconscionability looks at the bargaining process: was one party pressured into signing without a real chance to negotiate, or was the contract buried in fine print designed to prevent understanding? Substantive unconscionability focuses on the terms themselves, such as a price wildly disproportionate to the value received or a one-sided cancellation clause. A contract is most likely to be struck down when both dimensions are present: an unfair process produced unfair terms.
Definite Enough to Enforce
A contract has to be definite enough for a court to figure out what was promised and whether someone failed to deliver.7Open Casebook. Restatement (Second) of Contracts 33 – Certainty An agreement to sell “some equipment” at an “undetermined price” is a textbook example of fatal vagueness. The more important a missing term is to the deal, the stronger the signal that the parties weren’t ready to be bound.
Minor gaps don’t automatically kill a contract. Courts can fill in incidental details using industry custom or what’s reasonable under the circumstances. For sales of goods, the Uniform Commercial Code goes further: a contract won’t fail for indefiniteness as long as the parties intended to make a deal and there’s a reasonably certain basis for a remedy.8Legal Information Institute. UCC 2-204 – Formation in General If the parties leave the price open, the UCC supplies a reasonable price at the time of delivery.9Legal Information Institute. UCC 2-305 – Open Price Term
When a Contract Must Be in Writing
Certain categories of contracts must be in writing to be enforceable. An oral agreement that would otherwise satisfy every element of formation can still fail if the statute of frauds requires a written record. The categories vary somewhat by jurisdiction, but the most common ones are:
- Sales of goods at or above a threshold price. Under the traditional UCC rule, contracts for goods priced at $500 or more need a writing signed by the party being held to the deal. Amended versions of the UCC raised this threshold to $5,000, though most states have not adopted the revision.10Legal Information Institute. UCC 2-201 – Formal Requirements; Statute of Frauds
- Real estate transactions. Contracts for the sale or long-term lease of land almost universally require a writing.
- Agreements that can’t be performed within one year. If the contract’s terms make it impossible to complete within twelve months of signing, it needs to be in writing. The test is whether performance within a year is possible under the contract’s terms, not what the parties expect or what actually happens.
- Promises to pay someone else’s debt. A guarantee to cover another person’s obligation if they default is generally unenforceable without a writing.
The writing doesn’t have to be a formal contract. A signed letter, email, or series of text messages can satisfy the requirement as long as the document identifies the parties, describes the subject matter, and is signed by the party against whom enforcement is sought. The statute of frauds is a defense rather than a formation requirement: a contract that should have been written but wasn’t can still be voluntarily performed, but the party who didn’t get it in writing loses the ability to force the issue in court.10Legal Information Institute. UCC 2-201 – Formal Requirements; Statute of Frauds
Defenses That Can Undo a Signed Contract
A contract that looks perfectly valid on paper can still be thrown out if one party’s agreement was obtained through coercion or deception. These defenses challenge whether genuine consent ever existed.
Duress
If your agreement was induced by an improper threat and you had no reasonable alternative but to go along with it, the contract is voidable at your option.11H2O. Restatement Second Contracts 175-176 Duress isn’t limited to physical threats. Economic duress counts too, like a supplier threatening to withhold critical parts during a production deadline unless you agree to a massive price increase, knowing you have no other source. The question is whether the threat was wrongful and whether it genuinely left you without a practical choice.
Fraud and Misrepresentation
When one party lies about something material to the deal and the other party reasonably relies on that lie, the deceived party can void the contract.12Open Casebook. Restatement (Second) of Contracts 164 – When a Misrepresentation Makes a Contract Voidable The misrepresentation doesn’t have to be intentional fraud; a material inaccuracy that the other party justifiably relied on is enough. Intentional fraud opens the door to additional remedies. Fraudulent misrepresentation requires a false statement of fact, knowledge that the statement was false or reckless disregard for its truth, intent that the other party rely on it, actual reliance, and resulting harm. This is where sellers of businesses, real estate, and high-value goods most often get into trouble.
Who Can Sue Under a Contract
The default rule is simple: only the people who signed the contract can enforce it or be sued under it. If a homeowner hires a general contractor and the contractor stiffs a lumber supplier, the supplier can’t sue the homeowner under the homeowner-contractor agreement. The supplier wasn’t a party to that deal.
The major exception applies when the contract was specifically designed to benefit someone outside the agreement. If two parties enter a contract with the intent that performance will benefit an identified third person, that person becomes an intended beneficiary with the right to enforce the deal. A life insurance policy is the clearest example: the policyholder pays premiums to the insurer, and the named beneficiary can sue the insurer if it refuses to pay out. Someone who benefits only incidentally, like a neighbor whose property value rises because you landscaped under a contract with a landscaper, has no enforcement rights.
What You Can Recover for a Breach
When someone breaks a contract, the goal of the legal system is to put you in the position you would have occupied if the deal had gone through. That principle shapes every form of contract remedy, though the specific form varies depending on what was lost.
Expectation and Consequential Damages
The standard remedy is expectation damages: the monetary amount that gives you the benefit of your bargain. If you contracted to buy goods for $10,000 and resell them for $15,000, but the seller backed out and no replacement supplier was available, your expectation damages would be the $5,000 profit you lost. Consequential damages go further, covering indirect losses that flow from the breach, such as lost profits on downstream deals. These have guardrails: they must be reasonably foreseeable at the time the contract was signed and provable with reasonable certainty. Speculative future profits that nobody could have predicted don’t make the cut.
Specific Performance
Money doesn’t always fix the problem. When the subject of the contract is unique and no dollar amount would make you whole, a court can order the breaching party to actually perform. Real estate is the classic case; every parcel of land is legally unique, so if a seller refuses to close, a court can compel the transfer rather than just awarding damages. Specific performance also comes up with one-of-a-kind artwork, custom-made goods, and anything else where a replacement doesn’t exist. Courts won’t grant it unless the contract was fair, the requesting party has held up their end, and money damages are genuinely inadequate.
Liquidated Damages
Contracts often include a pre-set damages clause specifying how much one party owes if they breach. These liquidated damages provisions are enforceable as long as the amount was a reasonable estimate of the anticipated harm at the time the contract was signed. If the amount has no rational connection to likely losses and exists to punish breach, courts treat it as a penalty clause and refuse to enforce it. The label the parties chose doesn’t matter; courts look at substance. When a liquidated damages clause is struck down, the non-breaching party has to prove actual losses the old-fashioned way, which is often harder and more expensive than relying on the pre-agreed figure.
Deadline to Sue
Every breach of contract claim has a statute of limitations, a window during which you must file suit or lose the right to do so permanently. For written contracts, this period typically ranges from three to ten years, depending on the state. Oral contracts generally have shorter deadlines. The clock usually starts running from the date of the breach, not from the date you discovered it, though some states have discovery rules for certain types of claims. Once the limitations period expires, the breaching party can have the case dismissed regardless of how clear-cut the breach was. If you suspect a contract has been broken, get a professional assessment early rather than late.