DUI penalties depend—among other factors—on whether the defendant has prior DUI convictions. In other words, a first offender is typically looking at less severe consequences than a second or third offender. For example, on a first offense, a defendant doesn't usually end up serving any time in jail. But for a second or third conviction, it's common for jail time to be mandatory.

In most states, DUI convictions "washout" after a certain period of time. DUI convictions that have washed out don't count when determining whether the current offense is second or subsequent offense. Washout periods (also called the "lookback period") vary by state. However, it's fairly common for a DUI conviction to wash out after five, seven, or ten years.

Example: Ernie is a real lush, and he can't seem to stay off the road when he's been drinking. In the past 15 years, he's been convicted of driving under the influence four times, and he just got arrested for another DUI. The washout period in Ernie's state is seven years. Fortunately for Ernie, all four of his prior DUI convictions occurred more than seven years ago. So, if Ernie is convicted on his current DUI case, the court will sentence him as a first offender.

Some states don't have a washout period for DUI convictions. In these states, all prior DUI convictions count regardless of how long ago they occurred.

(Learn about the DUI/DWI laws in your state.)