Tortious interference is a business tort that occurs when someone improperly disrupts another party's contract or valid business expectancy, causing financial harm. It targets an outside party who interferes with a relationship between two others — not the party who simply breaks its own promise.
In Missouri, tortious interference is a common-law claim, meaning it comes from court decisions rather than a statute. The most important point to understand is that vigorous, lawful competition is never tortious interference, no matter how much business it costs you.
How tortious interference works in Missouri
Missouri recognizes two related forms of the tort: interference with an existing contract, and interference with a valid business expectancy (a probable future relationship, such as a likely renewal or a deal in advanced negotiation). Both require the same five-part proof.
To win, a Missouri plaintiff must prove each of the following:
- A valid contract or business expectancy — an enforceable agreement or a reasonable, probable future economic relationship.
- The defendant's knowledge of that contract or expectancy.
- Intentional interference 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.
- Resulting damages caused by the interference.
The fourth element, absence of justification, is the key battleground. The plaintiff carries the burden of proving it, usually by showing the defendant used improper means — fraud, misrepresentation, threats, or other independently wrongful conduct — or had no legitimate economic interest in the relationship it disrupted. Legitimate competition is generally not tortious.
Why it matters
Tortious interference comes up in everyday business disputes. Common scenarios include a rival lying to your customer to break up a signed contract, a competitor inducing a key supplier to breach its deal with you, or someone using confidential information to poach an account they had no honest stake in.
The practical line is sharp. A competitor who offers a lower price, faster delivery, or a better product — and wins your customer on the merits — has done nothing wrong, even if it costs you the account. The claim arises only when the competitor cheats: lying, threatening, defaming, or otherwise using improper means to cause the loss. Strong cases usually turn on the contemporaneous record of emails and communications showing what the defendant actually said and did.
Frequently Asked Questions
What are the elements of tortious interference in Missouri?
Five: a valid contract or business expectancy, the defendant's knowledge of it, intentional interference inducing a breach or termination, the absence of justification, and resulting damages. These come from Missouri court decisions, not a statute.
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, terms, or product is never actionable, even when it costs you the account. The claim arises only when the competitor lies, threatens, defames, or otherwise cheats.
Can I sue the other party to my own contract for tortious interference?
Generally no. Tortious interference is a claim against a third-party outsider. If the other side simply breaks its agreement with you, your claim is for breach of contract, and a party usually cannot tortiously interfere with its own contract.
Legal Disclaimer
This page provides general legal information about Missouri law and is not legal advice. It does not create an attorney-client relationship. Every situation depends on its own facts, deadlines, and documents; consult a qualified Missouri attorney before acting.