Whether beer needs to be "bagged" depends entirely on where you are in the airport journey and the volume of the container. For carry-on luggage, any liquid (including beer) must follow the 3-1-1 rule, meaning it must be in a container of 100ml (3.4 oz) or less and fit inside a single, clear, quart-sized resealable bag. Since most standard beer cans/bottles are 330ml or larger, they are typically prohibited in carry-on bags. However, if you purchase beer at a Duty-Free shop after passing through security, the retailer will place it in a Secure Tamper-Evident Bag (STEB), which allows you to carry it onto the plane (provided you don't open it during the flight). For checked baggage, beer does not need to be in a specific plastic bag by law, but it is highly recommended to "double-bag" or wrap bottles in leak-proof bags or padded sleeves to prevent breakage and avoid ruining your clothes if a can or bottle bursts due to cargo hold pressure changes.