A foreigner who enters into a fake marriage commits a crime. If convicted, the crime is a basis for removal from the U.S.
In Ashraf v. Lynch (PDF), (8th Circuit 4/22/16), Ashraf was charged with removability under 8 U.S.C. § 1227(a)(2)(A)(i) as an alien who has been convicted of a crime involving moral turpitude committed within five years after his admission. He was also charged with removability under 8 U.S.C. § 1227(a)(1)(G)(ii) as an alien who procured his visa by fraud.
Ashraf argued that the fake marriage occurred more than 5 years ago and so he should be exempted from removability due to a crime involving moral turpitude. The court rejected the argument because, after Ashraf obtained his green card, he later filed a request to remove conditional status on his green card. Those later filings continued the scheme to defraud the U.S. government. Ashraf could not avoid deportation for entering into a fake marriage.
Foreigners and also U.S. citizens must be careful about the criminal implications of entering into fake marriages.