Below is Carnival' new policy effective Feb. 2003. This was copied and pasted from Carnival's site. It most likely will not be enforced until all of their welcome aboard booklets and other documents are reprinted. Make special not of first paragraph.
What are your alcohol and consumption policies?
Guests are prohibited from bringing beverages of any kind (alcoholic and non-alcoholic) on board the ship for consumption. This includes: sodas, juices and bottled water.
However, we will make the following exception: If guests are celebrating a special occassion on board, they may bring ONE sealed bottle of wine or champagne per cabin. If the wine and/or champagne are brought to the Dining Room for consumption, a $10.00 corkage fee will be charged to the guest. Otherwise, the guest may drink the wine and/or champagne in the privacy of their cabin only. It may not be brought into any public lounge or room.
Alcohol purchased in a port-of-call: Alcoholic beverages purchased in any port-of-call will be appropriated at the gangway and stored onboard until the last night of the cruise, upon which it will be delivered to the guest’s cabin.
Alcohol purchased in ship gift shops: Alcoholic beverages of any kind purchased in the ship's gift shop will also be stored onboard and delivered to the guest's cabin on the last night of the cruise.
Consumption of alcohol on board: The minimum age for the purchase and/or consumption of alcoholic beverages while on board is 21 years of age. In the event that Bar/Restaurant/Gift Shop Staff are in question that the guest is under 21, they shall request picture identification prior to serving said guest.
Note: The legal drinking age onboard is 21 and is strictly enforced. We do not allow the purchase of drinks or bottles of liquor by adults for minors. Possession of alcohol by a minor will not be tolerated and any found will be confiscated, even if found in cabin.