In every state, you can get a DUI for driving while impaired by drugs or alcohol. And even if you aren't actually impaired, you can be convicted of a "per se" DUI for operating a vehicle with a blood alcohol concentration (BAC) of .08% or more.
The consequences of a DUI are always serious, even for a first offense. But the penalties are further enhanced for second-offense DUIs. Penalties for a second DUI often include not only fines, license suspension, and substance abuse education programs, but also mandatory jail time. Also, many states require second offenders to install ignition interlock devices (IIDs) in their vehicles.
What counts as a second DUI depends on the law of your state. In some states, a second DUI counts as a second offense only if it occurred within a certain period of time of the first offense. This period of time is sometimes called the DUI "look-back" period. For instance, some states count a DUI as a second offense only if it occurred within ten years (the look-back period) of a first DUI. In other states, a DUI counts as a prior forever: A second DUI will count as a second offense regardless of how long ago the first happened.
DUI laws vary by state, including those for second-offense DUIs. See our state-specific articles to learn about the laws for second-offense DUIs in your state.