39 U.S.C. § 3018: Civil Penalties for Mailing Hazardous Materials

The penalty for mailing hazardous materials through the U.S. Postal Service can reach $156,422 per violation after the January 2025 inflation adjustment, and that figure is only the starting point.¹ Under 39 U.S.C. § 3018, the sender is also liable for cleanup costs and any damages the shipment causes, and the way violations are counted means a single week of noncompliant shipping can generate six- or seven-figure exposure.²

How the Dollar Figures Actually Stack Up

The statutory range runs from $393 to $156,422 per violation after inflation adjustment.¹ The original statutory floor and ceiling were $250 and $100,000.²

What matters more than the ceiling is how the count works. Section 3018 creates two separate multipliers, and they stack:

Each noncompliant package is its own violation. Ten packages in one afternoon means ten violations.
Each day a noncompliant item stays in the mail is also its own violation. A package that spends four days in transit adds four more.

Those counting rules come from the statute’s “separate violations” subsection.² The math is why routine shippers who skip hazmat rules can face catastrophic assessments from what feels like a small mistake.

Liability reaches whoever mails the material or “causes” it to be mailed, so manufacturers and distributors who arrange the shipment cannot hide behind the person who dropped it off. It also reaches anyone who sells packaging marketed for mailing hazardous material that fails to meet Postal Service or DOT specifications. The statutory definition of “person” covers individuals, corporations, and partnerships alike.²

The Everyday Items That Trigger It

Most people who get caught are not shipping explosives. They are shipping consumer goods that carry a hazmat designation without realizing it. Common examples include:

Perfume and cologne (flammable due to alcohol content)
Lithium batteries and the phones and laptops they power
Aerosol cans such as hairspray, spray paint, and insecticide
Nail polish remover containing acetone
Dry ice
Old mercury thermometers

The broader categories are the ones you would expect: explosives, flammable liquids and gases, corrosives, radioactive materials, compressed gases, poisons, and infectious agents. Dropping any item that falls within these classes into a Priority Mail box without following the rules is enough to trigger § 3018.

“I Didn’t Know” Is Usually Not a Defense

Penalties attach when a person “knowingly” violates the statute, but knowing is defined broadly. It covers both actual knowledge of the facts and what a reasonable person exercising reasonable care would have known in the same circumstances.² If a reasonable person shipping personal-care products would have checked whether perfume was flammable, claiming you never thought about it does not get you off the hook. Willful ignorance carries the same liability as actual knowledge.

Cleanup Costs and Damages Come on Top

The civil penalty is only one layer. Section 3018 also makes the sender responsible for all cleanup costs tied to the violation and for any damages that result.² If a leaking package contaminates a sorting facility or a mail truck, decontamination is on you. If a postal worker is injured or other customers’ mail is destroyed, compensatory damages are added. The Postal Service can pursue penalty, cleanup, and damages in a single enforcement action, and these amounts are additive rather than alternative.

What Determines the Amount Within the Range

The Postal Service does not automatically go to the ceiling. The statute directs it to weigh several factors when setting a specific penalty:²

The nature and gravity of the violation. Unstable explosives draw harsher treatment than a mislabeled low-risk consumer product.
The sender’s degree of culpability. Deliberate concealment pushes toward the ceiling; a good-faith packaging error still generates liability but lands lower.
Prior violations. Repeat offenders see escalating penalties.
Ability to pay. USPS considers whether the amount would put the sender out of business.
Impact on operations. Facility evacuations, processing delays, and disruption to other customers’ mail weigh against the sender.
Other matters justice requires, a catch-all giving USPS discretion.

In practice, intentional concealment and a history of prior violations are the factors that most reliably drive penalties toward the top. Self-reporting an accidental mailing and cooperating with the investigation is a very different posture than packing hazardous goods in unmarked boxes on purpose.

Are Small Quantities Allowed?

Not every hazardous material is banned outright. The Department of Transportation’s Limited Quantity provision permits reduced requirements for certain materials in small enough amounts, but only if the specific material has an exception listed in Column 8A of the Hazardous Materials Table at 49 CFR § 172.101. The responsibility for checking sits entirely with the mailer.³

Even with a Limited Quantity exception, what you can do depends on how the package moves:

Surface (ground) mail. Limited-quantity materials may travel domestically by surface. They are prohibited in Priority Mail Express and Priority Mail, and applying surface-only markings to those services to sidestep air restrictions is itself a violation.⁴
Air mail. Limited-quantity items can only fly if they are reclassified as a Consumer Commodity under ID8000, which requires additional markings, a DOT Class 9 label, and a Shipper’s Declaration for Dangerous Goods in triplicate on the outside of the package.⁴
International mail. Limited-quantity surface materials are prohibited entirely.

Getting the label right on an authorized shipment matters too. Mailing an allowable material in the wrong packaging or with the wrong markings still counts as a prohibited act under § 3018(b), which reaches violations of any regulation restricting the time, place, or manner of mailing hazardous material.² Right material, wrong packaging, full penalty framework.

If you are unsure whether your item qualifies, the Postal Service’s Pricing and Classification Service Center can issue a ruling. Guessing is expensive.

How to Contest a Penalty

USPS cannot impose a penalty without giving you notice and an opportunity for a hearing.² The process begins with a formal Complaint served on you alleging a § 3018 violation. You then have 30 days to file a written Hearing Petition with the Recorder through the Judicial Officer’s electronic filing system.⁵

The petition has to identify you, state when you received the Complaint, and say whether you want an oral hearing or a decision on the written record. You must admit or deny each specific allegation and set out any defenses. If you want an oral hearing, propose a city and explain why.

Miss the 30 days and the Complaint goes to a Presiding Officer who decides based solely on what USPS has alleged, without your side.⁵ USPS also has authority to compromise a claim, meaning it can negotiate a reduced amount before pursuing collection in federal court.²

How Long USPS Has to Come After You

Section 3018 does not set its own limitations period. The general federal rule at 28 U.S.C. § 2462 gives the government five years from the date the claim first accrued to begin an action to enforce a civil penalty.⁶ Because per-day violations accrue on different dates, the effective enforcement window for a multi-day shipment can extend beyond five years from the original mailing.

When assessed penalties, cleanup costs, and damages go unpaid, USPS can sue in federal district court to collect the full amount.² The court’s judgment can sweep in the original fines along with emergency response and facility remediation costs. Ignoring a penalty notice does not make it go away; it usually ends in a federal judgment for everything USPS assessed.

1
Federal Register. Inspection Service Authority; Civil Monetary Penalty Inflation Adjustment
2
Office of the Law Revision Counsel. 39 USC 3018 – Hazardous Material
3
United States Postal Service. Publication 52 – Hazardous, Restricted, and Perishable Mail
4
United States Postal Service. Publication 52 – Hazardous, Restricted, and Perishable Mail
5
eCFR. 39 CFR Part 958 – Hazardous Materials
6
Office of the Law Revision Counsel. 28 USC 2462 – Time for Commencing Action