Tex. Alco. Bev. Code § 5.39

The commission shall adopt rules to standardize the size of containers in which liquor may be sold in the state and relating to representations required or allowed to be displayed on or in the containers. To accommodate the alcoholic beverage industry's conversion to the metric system, the commission shall adopt rules permitting the importation and sale of liquor in metric-sized containers as well as in containers sized according to the United States standard gallon system.