A more thorough explanation:

The phrase “under the influence” means that a person's ability to safely perform an activity is impaired due to the use of alcohol, drugs, or a combination of both. For example, if someone has had too much to drink, they may not be able to drive a car safely.

When a person is under the influence of alcohol, it means they have consumed enough alcohol to affect their actions, reactions, conduct, movement, or mental processes. This impairment can lessen their ability to operate a motor vehicle, which is why being under the influence of alcohol is an element of driving under the influence (DUI).

For instance, if a person's blood-alcohol content (BAC) is above the legal limit, it can support the inference that they were under the influence of alcohol at the time of the field sobriety test or blood test. The federal BAC limit is 0.08%, but state law may enforce a lower legal BAC limit.

Another example of being under the influence is when someone takes drugs that impair their ability to perform an activity safely. For instance, if someone takes prescription medication that causes drowsiness, they should not operate heavy machinery or drive a car.

Overall, being under the influence means that a person's ability to perform an activity safely is impaired due to the use of alcohol, drugs, or a combination of both. It is important to avoid such situations to prevent accidents and injuries.