The slayer rule, in the U.S. law of inheritance, stops a person inheriting property from a person they murdered (so that, for example, a murderer cannot inherit from parents or a spouse they killed).

While a criminal conviction requires proof beyond a reasonable doubt, the slayer rule applies to civil law, not criminal law, so the petitioner must only prove the murder by a preponderance of the evidence, as in a wrongful death claim meaning on the civil standard of proof of the balance of probability. Hence, even a slayer who is acquitted of the crime of murder can lose the inheritance by the civil court running the estate.

So far, 47 states have codified the slayer statute, either by adopting the Uniform Probate Code (UPC) or a version of the code that includes the slayer statute.^{[citation needed]}

At common law, American courts used two different theories when dealing with early slayer cases. Some courts would disinherit the slayer because of the public policy principle that a slayer should not profit from his crime (No Profit theory).

In Mutual Life v. Armstrong (1886), the first American case to consider the issue of whether a slayer could profit from their crime, the US Supreme Court set forth the No Profit theory (the term "No Profit" was coined by legal scholar Adam D. Hansen in an effort to distinguish early common law cases that applied a similar outcome when dealing with slayers), a public policy justification of slayer statutes: "It would be a reproach to the jurisprudence of the country if one could recover insurance money payable on the death of the party whose life he had feloniously taken."

Other courts were reluctant to disinherit a slayer in absence of a legislatively codified statute directing the court to do so (Strict Construction theory).

The Strict Construction theory (the term Strict Construction being coined by legal scholar Adam D. Hansen in an effort to distinguish this approach from earlier common law cases that dealt with similar situations involving the disinheritance of slayers) originated from Judge John Clinton Gray’s dissent in Riggs v. Palmer (1889). Judge Gray argued that the criminal law already established punishment for slayers, and that denying a slayer the estate would, in effect, impose significant further punishment beyond what was prescribed by statute. In his view, this was not something the court was permitted to do without an express, written law. The court, he contended, could not simply create or imagine such statutes in order to reach a morally pleasing result.

Slayer statutes codify the public policy principle that a murderer cannot profit from his crime. Slayer statutes provide a right of civil action to a victim's successors for the purpose of directing the victim's testate/intestate property away from the slayer. Such an action is brought by a successor, or other party of interest (e.g., life insurance company, bank), on behalf of the victim's estate. The slayer statute applies to both real and personal property that would have been acquired by intestacy or by will.