The precise definition used in court will vary from state to state; however, it will relate to the inability of the driver to operate a motor vehicle with the same caution characteristic of a sober person of ordinary prudence under the same or similar circumstances. It is not necessary for someone to have an alcohol level that is above the legal limit to be under the influence. However, most states do allow a jury to infer or presume that if someone is above the legal limit at the time the test was taken, and if the test was given close in time to the time of driving (within two or three hours), that the driver is under the influence. The manner in which the vehicle is driven is relevant, but not usually determinative in and of itself.

means lacking the normal use of mental or physical faculties. Impairment of a person's physical or mental faculties may be evidenced by a pattern of abnormal or erratic behavior or the presence of physical symptoms of drug or alcohol use. A student "under the influence" need not be legally intoxicated to trigger disciplinary action.

Under the Influence is a series of various artist compilation albums released by DMC UK. The tracks for each album are chosen by an artist or band to show the music that has influenced their work.

Any of a number of phrases meaning drunk on alcohol, high on drugs or both.