BAC on its own is not a federally controlled substance. Although it contains butalbital, it's on the Drug Enforcement Agency (DEA)'s list of exempted prescription products. But some states do classify BAC as a controlled substance.
Other combinations that contain BAC or are similar to BAC may be controlled substances. The DEA classifies Fiorinal, which contains butalbital, aspirin, and caffeine, as a Schedule III drug. That means that there’s a low to moderate risk of dependence or overuse.
In April 2022, the DEA proposed removing the exemption for BAC. The proposed rule change would add all products that contain butalbital to its list of Schedule III controlled substances.