What is the only thing that will sober an alcohol-impaired individual?

The only thing that will effectively sober an alcohol-impaired individual is time. When a person consumes alcohol, their body metabolizes it at a relatively constant rate, which cannot be sped up by any external remedies. While black coffee, cold showers, and fresh air may make someone feel more alert temporarily, they do not actually reduce the blood alcohol concentration (BAC) in the body. The liver is responsible for processing alcohol, and this process takes time, regardless of the individual's actions or environment. Thus, waiting for the body to eliminate alcohol is the only true way to achieve sobriety after drinking.