Should you take cannabis with you on a flight?

Although marijuana is legal for recreational use under California law (Proposition 64, effective January 2018), it remains illegal under federal law.

Specifically, marijuana is classified as a Schedule I controlled substance under the Controlled Substances Act (CSA), 21 U.S.C. § 812 — considered to have no accepted medical use and a high potential for abuse.

Thus, travelers passing through federal checkpoints — like Transportation Security Administration (TSA) screening areas or U.S. Customs and Border Protection (CBP) at international terminals — are subject to federal law.

TSA’s Official Policy on Marijuana

According to the TSA website:

“TSA’s screening procedures are focused on security and are designed to detect potential threats to aviation and passengers.

TSA security officers do not search for marijuana or other illegal drugs.

However, if any illegal substance is discovered during security screening, TSA will refer the matter to a law enforcement officer.”

Key points:

• TSA officers are not actively searching for drugs.
• However, if marijuana is found during a security search, TSA must report it to local authorities.
• At San Francisco International Airport (SFO), local authorities generally follow California law for domestic flights — often leading to warnings or confiscation, not arrest.
• However, CBP and federal laws applyto international flights. 

CBP’s Official Policy on Marijuana

According to U.S. Customs and Border Protection (CBP) :

“The importation of marijuana or cannabis products — even if for medical use or otherwise authorized under local law — remains illegal under federal law.”

Key points:

• Any attempt to export marijuana from the United States is illegal, even to countries where it might be legal.
• CBP officers enforce federal law strictly at all ports of entry, including airports.
• You could be detained, fined, arrested, or have your property seized if caught.
• It can also trigger immigration consequences (inadmissibility or removal proceedings) for non-U.S. citizens.

What Happens if You Are Caught with Marijuana Before Boarding an International Flight?

If you are caught with marijuana at TSA or CBP checkpoints while preparing to board an international flight:

TSA will detain you and refer you to local or federal law enforcement.

CBP officers (who have broader authority at international terminals) may search your luggage and person under federal jurisdiction.

Federal charges could be filed, including:

• Possession of a controlled substance (21 U.S.C. § 844)
• Attempted exportation of controlled substances (21 U.S.C. §§ 953 and 960)
• Smuggling charges (18 U.S.C. § 545)

Possible outcomes:

• Arrest and criminal prosecution
• Civil penalties (fines)
• Permanent seizure of property (including cash or electronics)
• Immigration consequences (for green card holders, visa holders, and visitors)

Possible Legal Defenses

If a traveler is charged under federal law, the following defenses could be raised depending on the circumstances:

1. Lack of Knowledge

• Arguing that you were unaware the marijuana was in your bag.
• It is particularly plausible if someone else packed the bag (e.g., sharing luggage, rental gear, or borrowed bags).

Legal Principle: Knowledge is key to possession charges under federal law (U.S. v. Lugo-Guadiana, 524 F.2d 958 (9th Cir. 1975)). 

2. Medical Necessity (Extremely Rare)

• Arguing that the possession was due to medical necessity to treat a serious medical condition.
• Very difficult under federal law because marijuana has no accepted medical use federally (Schedule I).
• Courts have generally rejected this marijuana defense (United States v. Oakland Cannabis Buyers’ Cooperative).

3. Small Quantities for Personal Use

• In some cases, defense counsel can negotiate a civil compromise for minor possession amounts — especially if there is no intent to distribute/export.
• Result: Potential pretrial diversion, fines, or dismissal after compliance with conditions.

4. Improper Search and Seizure

If the TSA/CBP officers violated Fourth Amendment protections — such as illegal search beyond the scope of a security screening — a motion to suppress evidence could be filed.

Caveat: Under the border search exception, courts tend to be very deferential to searches conducted at the border or international points of exit. 

Practical Tip for Travelers

• Do not travel internationally with marijuana.
• Even legal possession under California law can lead to severe federal penalties if you attempt to board an international flight.
• If you need to carry prescription medication, ensure it is federally approved, correctly labeled, and declared to TSA/CBP if necessary.

Conclusion

While California law permits adult recreational marijuana use, federal law still strictly prohibits it, especially in the context of international travel.

Travelers departing from San Francisco International Airport must understand that federal authorities enforce these laws at international terminals, regardless of local legalization. The same is true at other international airports within the United States.

If you face charges, contact a federal criminal defense attorney immediately to evaluate potential defenses and mitigate the consequences.

• SFO (San Francisco International Airport) provides “Marijuana Amnesty Boxes” at security checkpoints where travelers can voluntarily discard marijuana before flying.
• Border search exception gives CBP broad authority to search without a warrant or probable cause.
• Intent to distribute/export aggravates penalties heavily, even for relatively small quantities.

Source

Robison, F. (2015). Going Green: Legal Considerations for Marijuana Investors and Entrepreneurs. American University Business Law Review. https://digitalcommons.wcl.american.edu/aublr/vol6/iss1/6/