He can't simply get his conviction vacated. He has to have legal grounds under CPL section 440.10. You can try the pardon route but that's a super long shot. Consult a criminal defense lawyer.
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No. A pardon is not a realistic option. It is very hard to successfully vacate a criminal conviction. Depending on the facts, he may be able to file a motion to vacate his conviction on the grounds he was not advised of the immigration consequences of his guilty plea. You need to consult with both a criminal defense and an immigration attorney.
Assuming this happened in NY, you cannot expunge. A pardon is an extraordinary event, and you don't state anything about your husband which would make him a candidate. Vacating the crimnal charge would mean restoring the charge and then having him acquitted at trial or trying for a disposition that would allow him to remain in the US (i.e. re-enter). If that is possible, you will have to consult an immigration attorney.
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