The carry-on crowd knows the TSA’s familiar 3-1-1 rule well.
3-1-1 for carry-ons: 3.4 ounce (100 ml) bottles or less; one quart-sized, clear, plastic, zip-top bag; one bag per passenger placed in the screening bin. The one-quart bag limits the total liquid volume each traveler can bring on board.
Most travelers pack by that standard and move through security without trouble. But if you’re arriving in the United States on an international flight and have a connecting domestic leg, duty-free purchases such as liquor or perfume can be a concern because of additional security screening at your connecting gateway.
Good news: as of Jan. 31, the rules were clarified to allow certain duty-free liquids in excess of 100 ml in carry-on baggage for passengers arriving internationally with a connection. The key condition is that the items must be bought at duty-free shops and sealed in secure, tamper-evident bags.
There are important limitations. To be allowed through, duty-free liquids must be presented in secure, tamper-evident bags and be capable of being screened and cleared at TSA checkpoints. Items that cannot be effectively screened—such as liquids in opaque, ceramic, or metallic containers—may be subject to confiscation.
When purchasing duty-free liquids before an international flight to the U.S., ask for the required tamper-evident packaging and keep your receipt handy to speed the screening process. Follow these rules, and you can often enjoy duty-free finds without worrying about the 3-1-1 restriction on your connecting flight.