When a competitor lies to your customer to break up a signed contract, or sabotages a deal you were about to close, the harm is real even though the competitor never signed anything with you. Missouri law calls this tortious interference — and it is a powerful but tightly limited claim. To win, you must prove five specific elements, and the one that most often decides the case is whether the defendant acted without justification.
Missouri recognizes two related versions of the tort: interference with an existing contract, and interference with a valid business expectancy (a probable future relationship). Both are common-law claims — they come from Missouri court decisions, not a statute — and both require the same five-part proof. The critical point to understand from the start is that vigorous, lawful competition is never tortious interference, no matter how much business it costs you.
The five elements Missouri requires
To establish tortious interference with a contract or a business expectancy, a Missouri plaintiff must prove each of the following:
- A valid contract or a valid business expectancy. Either an existing, enforceable agreement, or a reasonable and probable expectation of a future economic relationship.
- The defendant's knowledge of that contract or expectancy.
- Intentional interference by the defendant that induced or caused a breach or termination of the relationship.
- The absence of justification — the defendant had no legal right or privilege to act as it did.
- Damages resulting from the interference.
Every element must be met. A plaintiff who proves a broken deal and lost profits but cannot show the absence of justification will lose, because that fourth element is what separates a tort from ordinary, protected competition.
A valid contract or business expectancy
The first element sets the floor. Contract interference requires an actual, enforceable agreement — the defendant induced one party to breach it. Business-expectancy interference is broader but harder: it reaches probable future relationships, such as a renewal a customer was likely to sign, a deal in advanced negotiation, or an established pattern of repeat orders. But the expectancy must be reasonable and probable, not a mere hope or the theoretical possibility of doing business with the world at large. Courts routinely dismiss expectancy claims built on speculative or generalized hopes of future profit.
Knowledge and intentional interference
The defendant must have known about the contract or expectancy — you cannot intentionally interfere with a relationship you do not know exists. And the interference must be intentional and active: the defendant did something to induce or cause the breach or termination, such as persuading, threatening, or deceiving the other party. Conduct that merely has the incidental effect of making performance harder, without the defendant intending to disrupt the relationship, generally will not satisfy this element.
The absence of justification — the heart of the case
The fourth element, absence of justification, is the most important and most frequently litigated. Missouri places the burden on the plaintiff to prove that the defendant's conduct was unjustified — it is not a defense the defendant must raise.
How does a plaintiff carry that burden? Missouri courts generally require a showing of one of two things:
- The defendant used improper means, or
- The defendant had no legitimate economic interest in the relationship it disrupted.
Improper means
If the defendant had any legitimate interest of its own at stake — its own contract, financial stake, or competitive position — the plaintiff can only establish absence of justification by proving the defendant used improper means. Improper means are acts that are wrongful independent of the interference itself, such as:
- Misrepresentation or fraud — lying about the plaintiff to the customer.
- Threats , intimidation, or coercion.
- Violence or destruction of property.
- Defamation or other unlawful or independently tortious conduct.
- Breach of a duty the defendant owed (for example, misusing confidential information).
The unifying idea: the defendant won the business not by outcompeting the plaintiff, but by cheating. A rival who tells your customer a knowing falsehood — that you are insolvent, that your product is dangerous, that you are about to stop shipping — and thereby breaks up the deal has used improper means. The same rival who simply offered a lower price, faster delivery, or a better product has not.
No legitimate economic interest
The other path applies when the defendant had no legitimate interest of its own to protect. Someone who interferes purely to harm the plaintiff — out of spite, malice, or to injure a competitor it has no honest stake in competing against — cannot claim the competition privilege, because there was no genuine economic interest justifying the interference in the first place.
Why ordinary competition is not actionable
This is the single most important practical takeaway. Missouri law actively protects competition, even aggressive competition. A business is free to:
- Solicit another company's customers, including under-contract customers whose agreements are terminable.
- Offer better prices , terms, or products to win business away.
- Advertise truthfully against a rival.
- Pursue the same prospects, deals, and opportunities.
None of this is tortious interference, even when it directly causes you to lose a customer or a deal, because the competitor is exercising its own legal and economic rights. The privilege of fair competition is precisely what the absence-of-justification element protects. Losing business to a better or cheaper competitor is the market working as intended — not a tort. The line is crossed only when the competitor abandons legitimate competition for improper means.
You generally cannot interfere with your own contract
A recurring trap is suing the wrong party. Tortious interference is a claim against a third party — an outsider who disrupts a relationship between two others. As a general rule, a party to a contract cannot tortiously interfere with that same contract. If the other side simply breaks its promise to you, your claim is for breach of contract, not tortious interference.
This principle also limits claims against a company's own agents, officers, and employees. Because they generally act on behalf of the contracting party (the company), they are usually not treated as the kind of third-party stranger who can interfere — unless they acted entirely outside their authority and against the company's interests for purely personal reasons. Trying to reframe a breach-of-contract dispute as tortious interference against the breaching party or its agents is a common pleading mistake that defendants move quickly to dismiss.
Damages and remedies
The fifth element is damages — the plaintiff must have suffered actual harm caused by the interference. Typical recovery includes the lost profits or benefit of the bargain from the contract or expectancy that was destroyed. Where the defendant's conduct was outrageous, willful, or malicious, punitive damages may also be available, subject to Missouri's statutory standards and caps. And where interference is ongoing, a plaintiff may seek injunctive relief to stop it. As with other business torts, the strength of a tortious-interference case often turns on the contemporaneous record — emails, communications, and documents showing what the defendant said to the customer and why the deal really fell apart.
Frequently Asked Questions
What are the elements of tortious interference in Missouri?
Five: (1) a valid contract or business expectancy; (2) the defendant's knowledge of it; (3) intentional interference inducing a breach or termination; (4) the absence of justification; and (5) resulting damages. It is a common-law claim, so it is not tied to a statute — these elements come from Missouri court decisions.
What does "absence of justification" mean?
It means the defendant had no legal right or privilege to do what it did. The plaintiff must prove this, usually by showing the defendant used improper means — fraud, misrepresentation, threats, violence, or other independently wrongful conduct — or had no legitimate economic interest in the relationship it disrupted.
Can I sue a competitor for taking my customer?
Only if the competitor used improper means. Missouri protects vigorous competition, so offering a better price, better terms, or a better product is never actionable, even if it costs you the account. The claim arises only when the competitor lies, threatens, defames, or otherwise cheats to cause the loss.
What counts as "improper means"?
Conduct that is wrongful independent of the interference itself: misrepresentation and fraud, threats and intimidation, violence, defamation, or breach of a duty (such as misusing confidential information). Simply competing hard and winning the business on the merits is not improper means.
Can a business expectancy that isn't a signed contract be protected?
Yes. Missouri recognizes interference with a valid business expectancy — a probable future relationship, like a likely renewal or a deal in advanced negotiation. But the expectancy must be reasonable and probable, not a mere hope or a generalized expectation of doing business with the public.
Can I sue the other party to my contract for tortious interference?
Generally no. Tortious interference is a claim against a third-party outsider. If the other side to your contract simply breaks it, your claim is for breach of contract. A party usually cannot tortiously interfere with its own contract, and the same limit often shields that party's officers and employees acting within their authority.
Legal Disclaimer
This guide provides general legal information about Missouri law and is not legal advice. It does not create an attorney-client relationship. Tortious-interference claims are fact-intensive and turn heavily on the absence-of-justification and improper-means analysis; consult a qualified Missouri attorney before pursuing or defending one.