Marriage fraud is common in the US even between citizens. People marry without love to share health care benefits or housing. Being from I high fraud country I have met people that have done all sorts of fraud just to come to the US and it has gotten worse since this country is no longer in the DV lottery. Federal courts are tied up with a lot of more important cases and they will take little notice of the USC that pockets a bit of money to marry for a bit. Unless they are doing this in a repeatable pattern it would be hard to prove it wasn't just a marriage gone bad after the non US partner simply sent their money to the US through their spouse. At the state level there is little about marriage fraud on the books and it is not a crime they chase after as it is hard to prove. Are there scary sounding penalties against this , yes. Do they actually go after anyone under that statue. not often.