E. If You Already Have a Prior Conviction
Many non-US citizens inquire of this office after they realize that their prior convictions affect their immigration status. Some people inquire about expungement. You should know that expungement, which is sealing the record from the public, will NOT work for the purpose of immigration. As explained repeatedly, once you are convicted the record will stay in the database forever. Even if you seal your conviction from the public, the Federal Government can still access your prior conviction. Expungement cannot protect non-US citizens with a conviction from an immigration point of view.
The only way to possibly fix this problem is to go back to the same court and ask for re-opening the case. This procedure is called Post Conviction Relief (PCR). PCR asks the court to reopen the case, and, if granted, you may be able to re-try the case to attempt to change the record of conviction.
You should note, however, that the PCR is only a petition; which means you can only APPLY for reopening the case. The court does not always grant it. There is no guarantee that you can reopen the case. The administrative deadline for a PCR in New Jersey is five (5) years. That means, within 5 years from the day of conviction, you can apply for a PCR. When you have important legal issues, you can sometimes go back more than 5 years. But based on my experience, you should bear in mind that the PCR can be more difficult and more often unsuccessful when you were convicted more than 5 years before.
Although PCR is an option for non-US citizens with a prior conviction, the reality is that many courts are reluctant to reopen a case. Courts have pressure to handle cases as efficiently as possible. Most courts are busy enough with current cases. There is not much incentive for courts to review old cases and reopen those. Especially these days, political and social pressures against illegal immigrants who commit crime are getting stronger. If you are interested in pursuing a PCR, the sooner you prepare, the higher chance of reopening the case you have.
If a court denies PCR, the options to improve an immigration issue are very limited. As you see, if you are a non-US citizen and get arrested, the best way is to retain a competent DWI & Criminal defense lawyer in the first place and investigate the consequences of conviction records on immigration status. You should take appropriate actions before it is too late.