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.