Defamation and Online Harassment Laws in Missouri

Defamation in Missouri is governed mainly by court-made common law. A plaintiff must show publication of a defamatory statement that identifies them, is false, was made with the required fault and damaged their reputation. A very old statute also makes it actionable to falsely and maliciously claim that someone committed adultery or fornication.

Sources1Digital Media Law Project, Missouri Defamation Law (citing Overcast v. Billings Mut. Ins. Co., 11 S.W.3d 62, 70 (Mo. 2000))2RSMo 537.110

Missouri has no criminal libel statute, so false statements about a person are handled through civil lawsuits. Online conduct that goes beyond defamation, such as harassment or stalking, can still be prosecuted under separate criminal laws.

Sources1Digital Media Law Project, Missouri Defamation Law (criminal libel)3RSMo 565.090 (harassment, first degree; version effective Jan. 1, 2017, to July 1, 2027)4RSMo 565.227 (stalking, second degree; version effective Aug. 28, 2017, to July 1, 2027)

An action for libel or slander must be brought within two years. Under Missouri's general accrual rule, the period starts when the damage is sustained and can be ascertained, and a Missouri appeals court applied this in a slander case to start the clock later than the date the statement was made.

Sources5RSMo 516.140 (with annotation to Thurston v. Ballinger, 884 S.W.2d 22 (Mo. App. W.D. 1994))6RSMo 516.100

Related guide: Statute of limitations for defamation in every state

The Missouri Supreme Court abandoned the old split between defamation per se and per quod in 1993. Plaintiffs no longer have to sort statements into those categories, but they must prove actual damages in every case, and the court has since held that this means showing harm to reputation, not emotional distress alone.

Source1Digital Media Law Project, Missouri Defamation Law (citing Nazeri v. Missouri Valley College, 860 S.W.2d 303 (Mo. 1993), and Kenney v. Wal-Mart Stores, Inc., 100 S.W.3d 809 (Mo. 2003))

Related guide: What defamation per se means

Missouri adopted the Uniform Public Expression Protection Act for civil actions filed on or after August 28, 2026. It covers claims based on speech, press, assembly, petition or association on a matter of public concern, and on statements in government proceedings, with some exceptions. A defendant can generally file a special motion to dismiss within 60 days of being served, other proceedings including discovery are generally paused while it is pending, a defendant who wins the motion is awarded attorney fees and costs, and a denial can be appealed right away. The older law, which only covered speech connected to public hearings or meetings, was repealed.

Sources7RSMo 537.5298RSMo 537.528 (repealed 2026; prior version effective Aug. 28, 2012)9Reporters Committee for Freedom of the Press, Anti-SLAPP Legal Guide: Missouri

Related guide: Anti-SLAPP laws by state

The Missouri Constitution allows the truth of a statement to be given in evidence in libel and slander cases, and statements that are true in substance are protected despite minor errors. Missouri courts also recognize protections for statements of opinion that do not imply provable facts, fair reports of official proceedings and witness statements in litigation. Public officials and public figures must prove actual malice, while private plaintiffs must show at least negligence.

Sources10Mo. Const. art. I, § 81Digital Media Law Project, Missouri Defamation Law (fault standards, privileges and opinion)

Missouri's stalking laws apply to a course of conduct of two or more acts, which can include communication by any means, so repeated online messages can qualify. Stalking in the second degree, purposely disturbing another person through such conduct, is generally a class A misdemeanor; stalking in the first degree, which adds factors such as threats or violating a protection order, is a felony. Amendments passed in 2026 that also cover "technological abuse conduct" take effect on July 1, 2027.

Sources4RSMo 565.227 (version effective Aug. 28, 2017, to July 1, 2027)11RSMo 565.225 (version effective Aug. 28, 2017, to July 1, 2027)12RSMo 565.002(4) (definition of course of conduct)13RSMo 565.227 (version effective July 1, 2027)

Related guide: Cyberstalking laws explained

Missouri's harassment laws apply to any act, online or offline, done without good cause and with the purpose of causing emotional distress. Harassment in the second degree is generally a class A misdemeanor; harassment in the first degree, where the act actually causes emotional distress, is a class E felony.

Sources14RSMo 565.091 (version effective Aug. 28, 2017, to July 1, 2027)3RSMo 565.090 (version effective Jan. 1, 2017, to July 1, 2027)

Related guide: Online harassment laws explained

It is a crime to knowingly post another person's name, home address, Social Security number, phone number or other identifying information online with intent to cause great bodily harm or death, or while threatening it. The offense is a class C misdemeanor, and a felony when the target is a police, corrections or parole officer, judge, commissioner or prosecutor, or their immediate family.

Source15RSMo 565.240

Related guide: Is doxxing illegal?

Intentionally sharing a private sexual image of an identifiable person to harass, threaten or coerce them is a class D felony when the image was obtained under circumstances showing it was meant to stay private and the sharer knew or should have known the person did not consent. The person shown can also bring a civil claim; a successful claim results in an award of $10,000 or actual damages, whichever is greater, plus attorney fees. Threatening to share such an image to gain something or to coerce someone is a separate felony.

Sources16RSMo 573.11017RSMo 573.112