A previous DUI/DWI conviction in another state may be included as a previous conviction and elevate or enhance the charge for a subsequent DUI/DWI in the driver’s current state of residence—just as if the driver had been convicted of the previous DUI/DWI offense in the driver’s current state of residence.

Whether a previous DUI/DWI conviction in another state is included or stacked on a DUI/DWI charge in the driver’s current state of residence will depend on whether the prosecutor on the current charge becomes aware of the previous conviction. The prosecutor will often become aware of a previous conviction by searching the National Driver Register database—which may include information regarding a driver’s license suspension or revocation provided by the other state in which the driver previously lived and was convicted of DUI/DWI. And if a driver receives a DUI/DWI while visiting another state, the police will notify the Department of Motor Vehicles (DMV) in both the state where the driver was charged with DUI/DWI and the state of the driver’s residence that issued the driver’s current license.

These laws vary from state to state and their application often includes some prosecutorial discretion on whether to include or stack a previous conviction for a DUI/DWI charge in another state on a current DUI/DWI charge in the driver’s state of residence. Some states include, calculate, or stack such a previous DUI/DWI conviction only when the law violated in the other state is sufficiently similar to the DUI/DWI law in the state where the current charge is pending.

In Connecticut (CT), a previous DUI/DWI conviction from another state can be considered when determining the severity of the charges and penalties for a subsequent DUI/DWI offense. Connecticut law allows for such out-of-state convictions to be treated as prior offenses if they are substantially similar to Connecticut's DUI/DWI laws. This means that if a person was convicted of a DUI/DWI in another state, and that offense is similar to what Connecticut defines as a DUI/DWI, it can be used to enhance the charges and penalties for a new DUI/DWI offense in Connecticut. The prosecutor in the current case may become aware of the previous conviction through the National Driver Register database or through notification from the DMV of the state where the offense occurred. The application of this law involves prosecutorial discretion, and the decision to include a previous out-of-state DUI/DWI conviction will depend on the specific circumstances of each case and the similarity of the laws between the states involved.