Most first- or second-time DUI (driving under the influence) offenses do not trigger immigration consequences. However, if you are in the U.S. with a green card (lawful permanent residence), a DUI conviction with aggravating factors or multiple DUI convictions may very well negatively affect your immigration status.
Although your green card gives you the legal right to live and work in the United States on a permanent basis, this does not mean that your green card is irrevocable. A green card holder can be placed in deportation proceedings, and subsequently removed from the United States, for crimes that are considered “deportable offenses.”
For a full list and explanation of deportable offenses, please see Grounds of Deportability: When Legal U.S. Residents Can Be Removed.
As you'll see, DUI is not specifically mentioned as a deportable offense in U.S. immigration law. However, depending on the severity of the DUI, it may be considered to match one of the various broader descriptions of deportable offenses.
For example, a DUI might be found to be a crime of moral turpitude (which in certain circumstances makes a person deportable) or an aggravated felony (which always makes one deportable).
To determine whether or not you may be placed into removal proceedings following a DUI conviction, consider the facts surrounding your arrest and whether additional charges were filed over and above the DUI. If your DUI involved “aggravating factors,” meaning facts that increased the severity of your DUI, there is a greater chance you will be found to fit one of the grounds of deportability mentioned above, and placed into removal proceedings.
For example, if you were convicted of a "normal" DUI, perhaps because you were pulled over by the police for swerving in the road or driving through a stop light, you were determined to have alcohol in your system above the legal limit, and this is your first or second offense, you likely will not be placed into removal proceedings following your conviction.
If, on the other hand, any of the following aggravating factors were present while you were driving under the influence, you may very well find yourself placed in deportation proceedings:
If immigration officers find that you are deportable, you will not be immediately removed from the United States. You will be placed in deportation court proceedings and given the opportunity to defend yourself. In such a situation, it is highly advisable that you obtain the services of an immigration attorney who specializes in deportation/removal proceedings and who has knowledge of your state’s criminal DUI law.
Keep in mind that even one DUI conviction may affect your ability to become a United States citizen. When applying for citizenship, you must show that you had five continuous years of good moral character. Even a simple DUI without aggravating factors may prevent you from showing good moral character within the required time frame.