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 Maryland, 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. Maryland law allows for such out-of-state convictions to be 'stacked' or included in the driver's record, potentially elevating the current charge to a more serious offense with harsher consequences. This is contingent upon the prosecutor's awareness of the prior conviction, which is often discovered through searches of the National Driver Register database. The database tracks information about drivers' license suspensions or revocations across states. Additionally, if a Maryland resident is convicted of a DUI/DWI in another state, law enforcement agencies are required to notify the DMV in both the state where the offense occurred and Maryland. The inclusion of a prior out-of-state DUI/DWI conviction in Maryland is subject to the similarity of the laws violated in the other state to Maryland's DUI/DWI laws. Prosecutorial discretion plays a role in the decision to include previous convictions in the current charge.