The carry-on passengers among us are intimately familiar with the TSA’s 3-1-1 rule.

3-1-1 for carry-ons: 3.4 ounce (100ml) bottle or less (by volume); 1 quart-sized, clear, plastic, zip-top bag; 1 bag per passenger placed in screening bin. One-quart bag per person limits the total liquid volume each traveler can bring.

We fastidiously pack accordingly and, hopefully, breeze through security. For those of us returning to the United States with connecting flights, though, it can be a pinch to pass up bargains on liquors or perfumes at airside duty-free shops because of security regulations at the connecting gateway.

Take heart — and take your chances. Effective Jan. 31, the rule for international inbound flights was amended to allow passengers traveling internationally into the United States with a connecting flight to carry liquids in excess of 100 ml in their carry-on baggage, provided the liquids were  purchased in duty-free shops and placed in secure, tamper-evident bags.

Some restrictions apply. Passengers will be allowed to travel with duty-free liquids providing they are presented in secure, tamper-evident bags that can be screened and cleared through TSA checkpoints. Liquids that cannot be effectively screened, including those contained in opaque, ceramic or metallic containers, will be confiscated.