Fifty people were killed yesterday during a mass shooting in Las Vegas, Nevada. When is a mass shooting or killings considered domestic terrorism by the U.S. federal government?

  • 1
    Considered by who? Commented Oct 3, 2017 at 1:48
  • Federal government. Commented Oct 3, 2017 at 2:05
  • 7
    Whenever it's politically beneficial to do so? Commented Oct 3, 2017 at 14:51

2 Answers 2


There is no single official U.S. definition of terrorism. Rather, each agency or law has its own definition which may conflict with other definitions.

Below are a few examples.

Dept. of Justice

According to the FBI website:

There is no single, universally accepted, definition of terrorism. Terrorism is defined in the Code of Federal Regulations as “the unlawful use of force and violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives” (28 C.F.R. Section 0.85).

The Code of Federal Regulations codifies federal regulations. It is law, but not in quite the same way as statutes are. The regulation mentioned above is specific to the Department of Justice. 28 CFR Sec. 0.85 mirrors this language, saying terrorism "includes":

the unlawful use of force and violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives

Therefore, for the Department of Justice, a mass shooting is not terrorism unless it promotes some political or social goal.

Department of State

However, federal law is inconsistent. For example, when describing the annual reporting requirements of the Department of State the law uses this definition of terrorism:

the term “terrorism” means premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents;

This is entirely different from the definition in the CFR. For example, any attack on military targets is never terrorism, and only subnational or clandestine groups can be terrorists.

State Level

Each state may also have their own definition. For example, the state of Kansas has this definition in law (formatting slightly altered from original):

Terrorism is the commission of, the attempt to commit, the conspiracy to commit, or the criminal solicitation to commit any felony with the intent to:

  • Intimidate or coerce the civilian population;
  • influence government policy by intimidation or coercion;
  • or affect the operation of any unit of government

In Kansas, any felony can be considered terrorism under the right circumstances, not just violent ones! Unlike the federal definitions, it does not include the objective furthering a social cause, which is another significant difference.


There is not any singular definition of terrorism in the United States. Different agencies and different laws will have entirely different and contradictory definitions.

  • 5
    There's this stigma now where the word "terrorism" is only applied to one group of people. Great answer by the way, thank you. Commented Oct 3, 2017 at 2:16
  • 1
    @Noah - Public opinion often looks very different than what's on the books. Commented Oct 3, 2017 at 2:21
  • 2
    That definition appears in a subsection of the CFR with no indication that it applies to any other subsection, let alone to "all agencies that deal with terrorism." It applies only in determining whether that subsection applies in identifying whether the FBI should lead a given investigation. Furthermore, you have significantly misquoted the definition by omitting the word includes. The use of that word means that things failing to meet that definition can also be terrorism (but don't forget that the definition applies only to that subsection).
    – phoog
    Commented Oct 3, 2017 at 3:57
  • @phoog - Thanks, I will check that out. The omission was not intentional. Commented Oct 3, 2017 at 11:32
  • I'm not sure "noncombatant targets" categorically excludes military. Are you sure it can't include soldiers who are located in a combat area? E.g., the Ft. Hood shooting was committed against soldiers who were nowhere near a combat zone and were not prepared for combat. Or am I misunderstanding what you meant?
    – jpmc26
    Commented Oct 3, 2017 at 22:03

There is one single Federal Definition of Domestic Terrorism, provided in Title 18, section 2331:

(5) the term “domestic terrorism” means activities that—
(A) involve acts dangerous to human life that are a violation of the criminal laws of the United States or of any State;
(B) appear to be intended—

(i) to intimidate or coerce a civilian population;
(ii) to influence the policy of a government by intimidation or coercion; or
(iii) to affect the conduct of a government by mass destruction, assassination, or kidnapping; and

(C) occur primarily within the territorial jurisdiction of the United States.

This was amended by the USA PATRIOT Act, of OCT 2001. This definition, established by Congress via their legislative authorities, is the foundation for the Federal Definition of domestic terrorism. The Code of Federal Regulations are merely the general and permanent regulations published by executive department and agencies of the Federal Government. This rule making is empowered by "enabling legislation" following acts passed by Congress. In a rule fight between the United States Code and the Code of Federal Regulations, the USC wins.

In order for an event to qualify as "Domestic Terrorism," it would have to meet the above guidelines from Title 18. As the investigation continues, this will depend on the indications of intent.

  • 4
    That "appear to be" bit is interesting.
    – phoog
    Commented Oct 3, 2017 at 4:55
  • @phoog The joy of legalese. Intelligence is focused on indications over proof. Commented Oct 3, 2017 at 4:59
  • 3
    @phoog Terrorists frequently don't announce their intent, it's just implied, so we're stuck with a subjective definition like this. There's probably similar language in the definition of "hate crime".
    – Barmar
    Commented Oct 3, 2017 at 8:06
  • 2
    @Barmar there isn't. See law.cornell.edu/uscode/text/18/249. Juries already make subjective judgments without needing weasel words like "appears" in statutory definitions. With a hate crime, the jury has to decide whether the accused was motivated by the victim's membership in a certain group or by the accused's perception that the victim is a member in such a group. The terrorist statute, on its face, allows a conviction even if there's demonstrably no actual intent under (B) but only an appearance of intent.
    – phoog
    Commented Oct 3, 2017 at 13:21
  • 3
    @Barmar the weasel word opens up the possibility of a reasonable person standard, meaning that jurors wouldn't have to determine whether they actually think the accused had such an intention, but only whether a "reasonable person" might make such a determination. It's another level of indirection that allows convictions under the statute even if the jury finds that there is no actual intention. Compare the distinction between "appearance of a conflict of interest" and "conflict of interest."
    – phoog
    Commented Oct 3, 2017 at 15:48

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