An arbitration agreement is not enforceable when it suffers the same defects that would void any contract, when a federal statute carves the dispute out of arbitration, when the party trying to compel arbitration has already waived that right by litigating, or when the clause simply doesn’t reach the dispute at hand. The Federal Arbitration Act makes written arbitration agreements “valid, irrevocable, and enforceable,” but the same section preserves every traditional contract defense, and Congress has since removed entire categories of claims from mandatory arbitration.1Office of the Law Revision Counsel. 9 USC 2 – Validity, Irrevocability, and Enforcement of Agreements to Arbitrate Here are the grounds that actually work.
Ordinary Contract Defenses
Section 2 of the FAA enforces arbitration clauses “save upon such grounds as exist at law or in equity for the revocation of any contract.”1Office of the Law Revision Counsel. 9 USC 2 – Validity, Irrevocability, and Enforcement of Agreements to Arbitrate That savings clause is the doorway for the standard contract defenses:
- Fraud or misrepresentation about something material to the decision to sign. If someone told an employee the arbitration clause was “just a formality” that wouldn’t limit their rights, that’s the kind of deception that can void consent.
- Duress or coercion, meaning genuine threats or improper pressure that goes beyond hard bargaining.
- Lack of capacity. Minors and people with severe cognitive impairments generally cannot be bound.
- Mutual mistake about something fundamental to the deal. Courts set a high bar here; the error has to go to the heart of the agreement, not a peripheral term.
One limit on these defenses matters: the defense has to be one that would also work against a non-arbitration contract with the same problem. A state rule that singles out arbitration clauses for worse treatment than other contracts is preempted by federal law. The Supreme Court made that clear in Kindred Nursing Centers v. Clark (2017), striking down a state rule that required specific jury-waiver language before an arbitration clause could be enforced.
Unconscionability
Unconscionability is the most frequently litigated ground, and courts analyze it on two dimensions.
Procedural Unconscionability
Procedural unconscionability asks whether the weaker party had any real choice. The classic case is an adhesion contract — a “take it or leave it” employment application or consumer agreement where the arbitration clause is buried in fine print with no room to negotiate. Courts weigh whether the terms were hidden, whether the signer had a meaningful chance to read and understand them, and how lopsided the bargaining power was.
Online agreements run through their own version of this test. Clickwrap setups that force you to scroll through terms and click “I agree” are generally enforceable. Browsewrap setups, where a website posts terms somewhere and claims that mere use equals consent, generally are not. Hybrid designs sit in between, and courts look at factors like whether the page was uncluttered, whether the terms sat near the action button, whether the formatting drew attention to them, and whether the type of transaction would lead a user to expect contractual terms.
Substantive Unconscionability
Even a clearly presented agreement can be unconscionable if its terms are one-sided enough. Red flags include arbitration fees so high they block access to the forum, rules that let one party go to court while forcing the other into arbitration, severe limits on available remedies, unreasonably short deadlines to bring claims, and discovery restrictions so tight that building a case becomes impossible.
Most courts apply a sliding scale. The more procedurally unfair the formation, the less substantively harsh the terms need to be, and the reverse. A contract of adhesion with moderately one-sided terms can be unconscionable; a freely negotiated agreement would need terms that are truly extreme. Some showing on both dimensions is usually required, but strength on one side compensates for weakness on the other.
The Delegation Clause Problem
Before any of these defenses reaches a judge, there’s a procedural hurdle that trips up many challenges. Modern arbitration agreements often contain a delegation clause, which gives the arbitrator — not a court — authority to decide whether the arbitration agreement itself is enforceable. In Rent-A-Center, West, Inc. v. Jackson (2010), the Supreme Court held that when an agreement delegates the enforceability question to an arbitrator, a court can only step in if the challenger attacks the delegation clause specifically, not the agreement as a whole.2Legal Information Institute. Rent-A-Center, West, Inc. v Jackson The Court went further in Henry Schein, Inc. v. Archer & White Sales (2019), ruling that courts cannot override a delegation clause even when the argument for arbitration appears “wholly groundless.”3Justia Law. Henry Schein, Inc. v Archer and White Sales, Inc.
Many agreements incorporate the rules of a major provider like the AAA or JAMS, and many courts treat that incorporation as clear evidence that the parties meant to delegate enforceability questions to the arbitrator. If you have a strong unconscionability argument but attack the whole agreement rather than the delegation provision itself, the court can send you to arbitration to sort it out there. The practical lesson: a challenge that targets the delegation language first, then the broader agreement, has a better chance of reaching a judge.
Waiver by Litigating First
A party with the right to compel arbitration can lose it by acting as though the agreement didn’t exist. The usual pattern: filing or defending a lawsuit, taking discovery, running up months of court filings, then abruptly demanding arbitration once the case turns unfavorable. In Morgan v. Sundance, Inc. (2022), the Supreme Court held that the party opposing arbitration does not need to show prejudice from the delay; the question is whether the party holding the arbitration right knowingly relinquished it by acting inconsistently with it.4Supreme Court of the United States. Morgan v Sundance, Inc.
Courts look at the totality of the circumstances: how much time passed, how far the litigation had progressed, and what costs the parties had already sunk. After Morgan, the analysis is more straightforward, because inconsistent conduct alone is enough.
Scope: The Clause Doesn’t Cover the Dispute
An arbitration clause can be perfectly valid and still not reach your dispute. The wording controls. A narrow clause covering disputes “arising from” a contract captures claims tied directly to the contract’s performance. Broader language covering “any and all disputes relating to” the agreement sweeps in claims that only touch the relationship indirectly. When the language is ambiguous, resolving scope often requires its own round of litigation.
Non-signatories complicate scope further. Someone who never signed can sometimes be forced into arbitration under theories like agency, estoppel, or third-party beneficiary status, and a non-signatory can sometimes use an arbitration clause to pull a signatory in.5American Arbitration Association. When Nonsignatories Can Be Compelled to Arbitrate These cases turn on state contract law and tend to be fact-heavy.
Transportation Workers
Section 1 of the FAA exempts “contracts of employment of seamen, railroad employees, or any other class of workers engaged in foreign or interstate commerce.” For these workers, the FAA simply doesn’t apply, and without the FAA, mandatory arbitration clauses in their work agreements lose their federal enforcement teeth.
The Supreme Court has read the exemption generously. In New Prime Inc. v. Oliveira (2019), it held that “contracts of employment” covers any agreement to perform work, so independent contractors who move goods across state lines are included.6Supreme Court of the United States. New Prime Inc. v Oliveira In Southwest Airlines Co. v. Saxon (2022), it held that airline cargo loaders qualify because they are physically involved in moving goods across state lines, even though they never leave the airport.7Supreme Court of the United States. Southwest Airlines Co. v Saxon The focus is on what the worker actually does, not on the employer’s business overall.
Truck drivers, cargo handlers, airline workers, and others whose jobs physically move people or goods across state or international borders may be able to defeat an arbitration clause in their work agreement regardless of whether they’re classified as employees or contractors.
Sexual Assault and Sexual Harassment Claims
Congress passed the Ending Forced Arbitration of Sexual Assault and Sexual Harassment Act in March 2022, adding Chapter 4 to the FAA. The rule is simple: at the election of the person alleging sexual harassment or sexual assault, no pre-dispute arbitration agreement or class action waiver is valid or enforceable for claims related to that conduct.8Office of the Law Revision Counsel. 9 USC 402 – No Validity or Enforceability The choice belongs to the person bringing the claim; they can still arbitrate if they want, but the other side cannot force it.
Two features make this law unusually strong. It covers both employment and consumer agreements under the FAA, and the statute expressly puts the question of whether the law applies in the hands of a court rather than an arbitrator, regardless of any delegation clause.8Office of the Law Revision Counsel. 9 USC 402 – No Validity or Enforceability That neutralizes the delegation trap that complicates most other challenges.
Claims That Can’t Be Arbitrated At All
Some disputes are off-limits for private arbitration no matter what the agreement says. Criminal prosecution is a government function and can’t be delegated to an arbitrator. Family law matters involving child custody, adoption, and guardianship also stay in court because judicial oversight protects children and public welfare standards.
For statutory claims like consumer protection, civil rights, and employment discrimination, the line is different. These claims can usually be arbitrated, but an arbitration agreement can’t strip away the substantive rights the statute provides. A clause requiring you to arbitrate a discrimination claim is likely enforceable. A clause requiring you to arbitrate it with a six-month deadline and no right to recover attorney’s fees, when the underlying statute provides both, may not be.
One Route That Doesn’t Work: Challenging a Class Action Waiver
Many arbitration agreements require claims to be brought individually and bar class or collective proceedings. Under current federal law, these waivers are enforceable. In AT&T Mobility v. Concepcion (2011), the Supreme Court held that the FAA preempts state laws banning class action waivers in arbitration agreements, even when grounded in unconscionability doctrine.9Justia Law. AT&T Mobility LLC v Concepcion In Epic Systems Corp. v. Lewis (2018), the Court held that arbitration agreements requiring individualized proceedings must be enforced as written, and that the National Labor Relations Act does not override that result.10Supreme Court of the United States. Epic Systems Corp. v Lewis The only significant exception is the sexual misconduct carve-out above. If your reason for wanting out of arbitration is really that you want to join a class, that argument will not get you there.