How does a dismissed arrest (or expunged criminal record) effect a K-1 visa outcome?
Arrests and criminal history and convictions are not necessarily a reason for a denial. If you check the box on a K-1 fiance visa that states that you were convicted of a crime, you'll need to supply or provide the court records, the police records, and any dispositions of that case. Even if your case was closed, your records were sealed or expunged, or an attorney told you that this will never show up on your record, it is not considered "gone" by the USCIS.
When they perform the fiance visa background check, any prior criminal history or convictions, any prior arrests, are going come up in this record. So it's very important that you be truthful and honest when you answer the questions and make sure that you provide the police records and court records. If you're unable to obtain the requested documents, in some cases, you can write a personal statement or letter describing the conviction or the arrest and give your side of the story. 'The adjudicator or consular officer is going to ask the fiance if they were aware of the criminal history, and they're going to present these documents to them. It's nothing really to be alarmed about or worried about, there's just some simple rules that you've got to follow.
We've successfully done K-1s for lots of people with criminal history. As the US citizen sponsor, your criminal background is not, in most cases, of concern. If you're the alien, then yeah, absolutely, it effects it. There's a public interest in not allowing people to immigrate who maybe have criminal background problems, so it depends.
If you are the US sponsor and are affected by IMBRA, you may have concerns. This includes crimes like domestic violence. See this article for more on that subject.