Some people enter into a marriage with a U.S. citizen or lawful permanent resident for the sole purpose of obtaining U.S. lawful permanent residence (a green card). They're not in love with, nor intending to create a life together with the U.S. citizen or permanent resident. They may even be paying the person to get married - though that's not a requirement.
These green-card motivated marriages are considered marriage fraud. U.S. Citizenship and Immigration Services (USCIS) has a zero tolerance policy towards such marriages.
USCIS believes that a substantial percentage of marriage-based green card filings are fraudulent. After all, getting a green card through marriage is one of the few ways that a person with no job skills, money to invest in a U.S. business, or other desirable characteristics under the U.S. immigration laws can obtain a green card. This provides enough motivation for many people to misuse the process.
Aside from being tipped off by someone -- in some cases, the U.S. citizen or permanent resident him- or herself -- USCIS's very application process is designed to weed out fraudulent marriages, as follows:
During the initial application process, the couple will have to submit documents showing that they are truly married and sharing a life together, such as wedding photos, children's birth certificates, mortgage or apartment documents, copies of joint bank statements, and so on. They'll also need to pass an interview at which the immigrant, and in some cases the U.S. citizen spouse, must persuade an immigration official that the marriage is not a fake.
If they don’t pass the first interview, the couple will have to undergo a fraud interview, at which the two are separately asked the same set of very personal questions -- everything from what color the curtains in their bedroom are to how they celebrated one spouse's last birthday to what form of birth control they use -- and then the answers are compared to see how well they match up. (For more on what to expect at these interviews, see What Happens at The Green Card Marriage Interview?)
After approval for the green card, the immigrant will have to get through a two-year period during which his or her lawful residence is only "conditional." That means that it will expire at the end of the two years if the immigrant doesn’t once again convince the immigration authorities (in this case, U.S. Citizenship and Immigration Services or USCIS) that the marriage is the real thing. The couple must jointly sign and file a Form I-751 and attach even more documents showing their shared life. At this point, some couples in sham marriages are tired of the charade and start living separately, which can make going from conditional to permanent residence even less likely.
Another opportunity for USCIS to review the immigrant's case comes up if and when the person applies for U.S. citizenship (naturalization). If, for example, the couple got divorced, USCIS might ask for further proof that the marriage was bona fide. If the immigrant fails to come up with convincing documents, not only would USCIS deny citizenship, but it would likely put the immigrant into removal (deportation) proceedings.
In case of an immigration marriage fraud, the alien will likely be deported and will be ineligible for immigration and entry into the United States in the future. In addition, both the alien and the U.S. citizen or lawful permanent resident may face criminal prosecution, including fines and imprisonment. Lawful permanent residents may themselves lose their lawful permanent resident status and be removed from the United States.