U.S. law defines and prosecutes terrorism through a layered system: two statutory definitions in 18 U.S.C. § 2331 that separate international from domestic acts, a designation process that puts foreign groups and individuals on government lists, and a set of criminal statutes, financial sanctions, and immigration rules that reach anyone who joins or supports a designated organization. There is no single “terrorism” crime in the federal code. Instead, prosecutors charge specific predicate offenses, material support violations, or sanctions breaches, and the terrorism label attaches through those charges rather than as a count of its own.
The Two Statutory Definitions
Section 2331 of Title 18 sets out both definitions. An act qualifies as international terrorism when it involves violence or conduct dangerous to human life that violates federal or state criminal law, appears intended to intimidate a civilian population or coerce a government, and occurs primarily outside the United States or crosses national borders in how it is carried out or whom it targets.1Office of the Law Revision Counsel. 18 USC 2331 – Definitions
Domestic terrorism uses nearly the same structure. The conduct must be dangerous to human life, break federal or state law, and appear intended to intimidate civilians, influence government policy through coercion, or affect government conduct through mass destruction, assassination, or kidnapping. The only real difference is geographic: domestic terrorism happens primarily inside U.S. territory.1Office of the Law Revision Counsel. 18 USC 2331 – Definitions
Why No One Gets Charged With Domestic Terrorism
The domestic terrorism definition does not create a standalone crime. Nobody is charged with “domestic terrorism” as its own offense. The definition works as a trigger for expanded investigative tools and as a gateway to other charges. Prosecutors handling domestic attacks lean on weapons offenses, hate crime statutes, or state murder laws instead.
The absence is deliberate. A formal domestic terrorism crime, or a designation list for domestic groups, raises First Amendment concerns about punishing political belief rather than violent conduct. The federal government keeps no equivalent of the foreign terrorist list for domestic groups, which means the sanctions that flow from foreign designation, including asset freezes and criminal liability for supporters, have no domestic parallel.
Federal Crimes of Terrorism
Federal law identifies dozens of specific offenses that count as a “federal crime of terrorism” when calculated to influence or coerce a government or to retaliate against government conduct. The list in 18 U.S.C. § 2332b(g)(5) includes destroying aircraft, using biological or chemical weapons, attacking government property with explosives, hostage-taking, assassinating federal officials, and financing terrorism.2Office of the Law Revision Counsel. 18 USC 2332b – Acts of Terrorism Transcending National Boundaries When one of these predicates is charged as a federal crime of terrorism, the label unlocks harsher sentencing and expanded investigative authority even though it never appears as its own count.
How Foreign Groups Get Designated
The Secretary of State can formally designate a group as a Foreign Terrorist Organization (FTO) under 8 U.S.C. § 1189. The designation requires three findings: the group is foreign, it engages in terrorist activity or retains the capability and intent to do so, and its activity threatens U.S. nationals or U.S. national security. The Secretary acts in consultation with the Attorney General and the Secretary of the Treasury.3Office of the Law Revision Counsel. 8 USC 1189 – Designation of Foreign Terrorist Organizations
Seven days before the designation becomes official, the Secretary notifies congressional leaders through classified channels. After that window, the designation is published in the Federal Register and takes immediate legal effect. Financial institutions holding any assets of the designated group may then be required by the Treasury Secretary to freeze all financial transactions involving those assets.3Office of the Law Revision Counsel. 8 USC 1189 – Designation of Foreign Terrorist Organizations
Executive Order 13224 and Specially Designated Global Terrorists
The FTO list is not the only tool. Executive Order 13224, issued after September 11, 2001, created a parallel system for designating individuals and entities as Specially Designated Global Terrorists (SDGTs). This authority is broader than the FTO process because it reaches specific people, financiers, and front companies, not just organizations.
The Secretary of State can designate foreign persons who have committed, pose a significant risk of committing, or participated in training to commit acts of terrorism threatening U.S. security. Treasury can then build outward, targeting anyone owned or controlled by, acting on behalf of, or providing financial or material support to an already-designated person or entity.4eCFR. 31 CFR Part 594 – Global Terrorism Sanctions Regulations That derivative authority is what lets Treasury follow the money through layers of facilitators.
Both designation types trigger asset freezes, but the criminal consequences differ. FTO status automatically makes it a federal crime to knowingly provide material support to the group and imposes immigration restrictions on members by virtue of membership. SDGT status prohibits U.S. persons from any transaction with the designated individual or entity and freezes U.S.-held assets, with criminal liability running through the sanctions regulations rather than the material support statute.
Material Support: The Workhorse Statutes
Two statutes carry most of the weight in federal terrorism prosecutions, and the distinction between them matters.
Section 2339A: Support Aimed at a Specific Crime
Section 2339A makes it a crime to provide material support knowing or intending that it will be used to carry out one of the predicate federal crimes of terrorism. The focus is on the use, not the recipient. You can violate it by helping an individual with no connection to any designated group, so long as the support goes toward a qualifying offense. The maximum sentence is 15 years, or life if anyone dies.5Office of the Law Revision Counsel. 18 USC 2339A – Providing Material Support to Terrorists
Section 2339B: Support to a Designated Group
Section 2339B flips the focus. It criminalizes knowingly providing material support to a designated FTO regardless of whether the support is tied to any specific attack. Sending money to an FTO for what a donor believes are charitable purposes still violates the statute. Maximum sentence: 20 years, or life if anyone dies.6Office of the Law Revision Counsel. 18 USC 2339B – Providing Material Support or Resources to Designated Foreign Terrorist Organizations
The government must prove the defendant knew the group was designated, or knew it engaged in terrorist activity. Prosecutors do not need to show intent to further any particular attack.6Office of the Law Revision Counsel. 18 USC 2339B – Providing Material Support or Resources to Designated Foreign Terrorist Organizations
What Counts as Material Support
The statutory definition is deliberately wide. Material support or resources covers any property or service, including currency, financial services, lodging, training, expert advice or assistance, safehouses, false identification documents, communications equipment, weapons, explosives, personnel, and transportation. Only two things are carved out: medicine and religious materials.5Office of the Law Revision Counsel. 18 USC 2339A – Providing Material Support to Terrorists
The Supreme Court tested that breadth in Holder v. Humanitarian Law Project (2010). A group of U.S. citizens wanted to train a designated organization in how to use international law to resolve disputes peacefully. The Court upheld the statute 6–3, ruling that even training in nonviolent legal advocacy counts as prohibited material support when provided to an FTO. The majority reasoned that any form of support frees up other resources the group can redirect toward violence, and that Congress was entitled to make that judgment. Good intentions are not a defense. If you knowingly provide training, expert advice, or personnel to a designated group, the statute reaches you regardless of whether your contribution was violent.
Financial Sanctions and OFAC
Treasury’s Office of Foreign Assets Control (OFAC) enforces the money side. When a person or group is designated, OFAC adds them to the Specially Designated Nationals (SDN) list. All U.S.-based property and financial interests of listed parties are blocked and cannot be transferred, withdrawn, or otherwise dealt in. Any transaction that violates the blocking order is void from the start and creates no enforceable legal rights.4eCFR. 31 CFR Part 594 – Global Terrorism Sanctions Regulations
Penalties are severe. Civil penalties can reach the greater of $377,700 per violation or twice the value of the underlying transaction. A willful violation can bring criminal fines up to $1,000,000 and up to 20 years in prison for an individual.4eCFR. 31 CFR Part 594 – Global Terrorism Sanctions Regulations
Immigration Consequences
A terrorism connection can permanently bar a foreign national from entering or remaining in the country. Under 8 U.S.C. § 1182, a person is inadmissible if they have engaged in terrorist activity, are a representative of a terrorist organization, or are a member of a designated group. The statute defines terrorist organization broadly enough to reach FTO-designated groups, groups designated separately by the Secretary of State, and even undesignated groups of two or more people who engage in qualifying activities.7Office of the Law Revision Counsel. 8 USC 1182 – Inadmissible Aliens
The bar reaches further than many expect. It applies to non-violent, non-financial forms of support. Providing training or expert advice to a designated group can trigger inadmissibility, and any foreign national found to be associated with terrorism can face deportation regardless of current lawful status.
Civil Lawsuits by Victims
Federal law lets terrorism victims recover money damages. Under 18 U.S.C. § 2333, any U.S. national injured in person, property, or business by an act of international terrorism can sue in federal court and recover triple the actual damages sustained, plus attorney’s fees.8Office of the Law Revision Counsel. 18 USC 2333 – Civil Remedies
Foreign governments normally enjoy sovereign immunity in U.S. courts. The Justice Against Sponsors of Terrorism Act (JASTA), enacted in 2016, cut a significant exception. Under 28 U.S.C. § 1605B, a foreign state loses immunity when a suit seeks money damages for physical injury, property damage, or death occurring inside the United States that was caused by an act of international terrorism and a tortious act of that foreign state or its agents, no matter where the foreign state’s conduct took place.9Office of the Law Revision Counsel. 28 USC 1605B – Responsibility of Foreign States for International Terrorism Against the United States Before JASTA, only countries formally designated as state sponsors of terrorism could be sued under the older exception. Four countries currently carry that designation: Cuba, North Korea, Iran, and Syria.
Getting Off a Designation List
Designations are not permanent. A designated FTO can petition the Secretary of State for revocation starting two years after the original designation, presenting evidence that circumstances have changed. The Secretary has 180 days to decide. If no petition-based review has occurred within a five-year window, the Secretary must conduct her own review to decide whether to keep the designation in place.3Office of the Law Revision Counsel. 8 USC 1189 – Designation of Foreign Terrorist Organizations
An organization denied revocation can seek judicial review in the D.C. Circuit Court of Appeals within 30 days. The court reviews only the administrative record, including any classified material the government submits, and applies a deferential standard. It can overturn a designation only if the Secretary’s decision was arbitrary, capricious, exceeded statutory authority, or lacked substantial support in the record. The court has treated the question of whether a group threatens national security as a political question inside the executive’s sole discretion, which narrows the scope of review further.
Individuals on OFAC’s SDN list as SDGTs can petition for removal by writing to OFAC at a designated email address. No attorney is required. The petition should include proof of identity, the listing details, and a detailed explanation of why removal is warranted, such as evidence that the basis for the designation no longer applies.10Office of Foreign Assets Control. Filing a Petition for Removal from an OFAC List The process is straightforward on paper. In practice, removals are rare, the government holds nearly all the informational advantages, and anyone considering a petition should expect a long timeline and limited transparency.