18 USC 175: Biological Weapons Offenses, Penalties, and Reach

18 U.S.C. 175 makes it a federal crime to knowingly develop, produce, stockpile, transfer, acquire, retain, or possess a biological agent, toxin, or delivery system for use as a weapon, or to help a foreign government or organization do the same. The primary offense carries a fine, imprisonment for any term of years, or life. A narrower possession offense, for holding biological materials in a type or quantity with no reasonable peaceful justification, carries up to 10 years. Threats, attempts, and conspiracies are punished the same as completed acts.

The Weaponization Offense Under Section 175(a)

Section 175(a) reaches anyone who knowingly develops, produces, stockpiles, transfers, acquires, retains, or possesses any biological agent, toxin, or delivery system for use as a weapon. It also covers knowingly assisting a foreign state or organization to do any of those things.¹

The statute does not stop at completed conduct. Attempting, threatening, or conspiring to commit any of these offenses carries the same potential penalty as carrying them out. A credible threat to deploy a biological weapon exposes the person to the same sentencing range as actually building one.¹

“For use as a weapon” is defined by exclusion. Handling biological materials for prophylactic, protective, bona fide research, or other peaceful purposes falls outside the offense. Everything else falls inside.¹

The Unjustified Possession Offense Under Section 175(b)

Section 175(b) is a separate, narrower crime: knowingly possessing a biological agent, toxin, or delivery system in a type or quantity that under the circumstances is not reasonably justified by a prophylactic, protective, bona fide research, or other peaceful purpose. Prosecutors do not have to prove the person intended to use the material as a weapon. They only have to show the possession makes no sense for any legitimate reason.¹

Section 175(b) carries up to 10 years in prison, a fine, or both. A microbiologist holding registered quantities of a pathogen for published work has a clear peaceful justification. Someone with no professional need stockpiling ricin does not.

The provision also excludes biological agents and toxins in their naturally occurring environment, so long as they have not been cultivated, collected, or otherwise extracted from that source. Undisturbed soil containing anthrax spores, for instance, falls outside 175(b).¹

What Counts as a Biological Agent, Toxin, or Delivery System

The controlling definitions sit in 18 U.S.C. 178, not in section 175 itself, and they are deliberately broad.

A biological agent is any microorganism or infectious substance — including bacteria, viruses, fungi, and bioengineered or synthesized components — capable of causing death, disease, or biological harm in humans, animals, or plants, or of contaminating food, water, or equipment, or of damaging the environment.²

A toxin is any toxic material produced by a plant, animal, or microorganism, or any recombinant or synthesized version of one. Engineered poisons and derivatives of naturally occurring toxins both qualify.²

A delivery system covers equipment or devices specifically designed to disperse a biological agent, toxin, or vector. The definition also reaches the vector itself, meaning a living organism or molecule capable of carrying an agent to a host. A genetically modified insect engineered to spread a pathogen counts, with no mechanical device required.²

Peaceful Uses That Fall Outside the Statute

Congress stated when it enacted Chapter 10 that nothing in the statute was intended to restrain or restrict peaceful scientific research or development. Universities, pharmaceutical companies, public health laboratories, and medical researchers routinely handle agents that would otherwise fall within the statute. Two conditions have to hold: the purpose has to be genuinely peaceful, and the type and quantity of the materials have to be reasonable for that purpose.

If those conditions are met, section 175(a)’s “for use as a weapon” element is not satisfied, and section 175(b)’s “not reasonably justified” element is not satisfied. The exception applies to the conduct, not to the person; a legitimate researcher who steps outside genuine research loses its protection.

What the Government Has to Prove

Both offenses require the government to prove the defendant acted knowingly. The person has to have been aware of what they were doing and of the nature of the materials involved. Accidental possession does not satisfy the standard.¹

Under section 175(a), prosecutors carry a heavier practical burden. They must show not just knowing handling of biological materials but that the handling was for use as a weapon, meaning for something other than a peaceful purpose. That element usually turns on circumstantial evidence: communications discussing intended harm, acquisition of materials with no plausible peaceful explanation, possession of weaponization equipment, or prior conduct suggesting hostile intent.

Under section 175(b), the government does not have to prove weapons intent. It only has to prove knowing possession of biological agents or toxins in a type or quantity with no reasonable peaceful justification.¹

For conspiracy charges, the government has to prove an agreement between two or more people to commit a prohibited act, plus at least one step taken to advance the plan, with the mental state judged separately for each co-conspirator.

Penalties Under Section 175 and Related Statutes

The section 175(a) offense carries a fine, imprisonment for any term of years or life, or both. The maximum applies whether or not anyone is harmed. Building a biological weapon can produce a life sentence even if it is never deployed.¹

Section 175(b) carries up to 10 years, a fine, or both.¹

When a biological weapon is actually used and someone dies, 18 U.S.C. 2332a authorizes the death penalty or life imprisonment. That statute covers anyone who uses, threatens, attempts, or conspires to use a weapon of mass destruction, and its definition of that term expressly includes weapons containing biological agents. Without a death, section 2332a still allows imprisonment for any term of years up to life.³

A single course of conduct can produce stacked charges. The same facts may support counts under section 175(a) for developing a weapon, section 175(b) for unjustified possession, and section 2332a for use or attempted use of a weapon of mass destruction, along with federal conspiracy counts. Cumulative sentences can be very long.

Restricted Persons Cannot Possess Select Agents at All

A companion statute, 18 U.S.C. 175b, bans certain categories of people from possessing select biological agents and toxins regardless of purpose. The peaceful-use exceptions that protect researchers do not apply to a restricted person.

Restricted persons include:

Anyone under indictment for or convicted of a crime punishable by more than one year in prison
Fugitives from justice
Unlawful users of controlled substances
Noncitizens unlawfully present in the United States, and nationals of countries designated as state sponsors of terrorism
People adjudicated as mentally defective or committed to a mental institution
Dishonorably discharged members of the armed forces
Members of designated terrorist organizations

A restricted person who knowingly possesses a select agent or toxin faces up to 10 years in prison. Authorized U.S. government activity is the one exception. Transferring a select agent to someone you know, or have reasonable cause to believe, is not properly registered under federal regulations carries up to five years. The “reasonable cause to believe” standard is lower than actual knowledge.⁴

Reach Beyond U.S. Borders

Section 175(a) applies to conduct outside the United States when the offense is committed by or against a U.S. national. A U.S. citizen who develops a biological weapon abroad can be prosecuted in federal court as if the conduct occurred at home. A foreign actor who targets a U.S. national abroad can also be reached.¹

Section 2332a extends the same framework to the use of weapons of mass destruction against U.S. nationals outside the country, with penalties up to and including death when the attack is fatal.³

1
Office of the Law Revision Counsel. 18 USC 175 – Prohibitions With Respect to Biological Weapons
2
Office of the Law Revision Counsel. 18 USC 178 – Definitions
3
Office of the Law Revision Counsel. 18 USC 2332a – Use of Weapons of Mass Destruction
4
Office of the Law Revision Counsel. 18 USC 175b – Possession by Restricted Persons