Extract from:
Fiance & Marriage and Visas: A couple's guide to US Immigration
1. What Is a Sham Marriage?
A sham marriage is one that is entered into in order to get around the U.S. immigration laws. For a marriage to be valid under the law, it is not enough that the couple had a real marriage ceremony and got all the right governmental stamps on their marriage certificate. They have to intend to live in a real marital relationship following the marriage ceremony -- and prove their intention through their actions. If the couple doesn't intend to establish a life together, their marriage is a sham. (For more on what USCIS considers to be a real or bona fide marital relationship for purposes of green card eligibility, see Chapter 2, Section B.)
2. Will You Get Caught?
Detecting marriage frauds is a top priority for USCIS. USCIS officers still quote a survey from the 1980s which found that up to 30% of marriages between aliens and U.S. citizens are suspect. That survey has since been shown to be deeply flawed, but its legacy lives on.
In order to detect frauds, the immigration authorities require a lot of proof that a marriage is real, including more documentation than for other family-based immigration applicants. They subject marriage-based immigrants to a longer and more detailed personal interview and a two-year testing period for couples who have been married fewer than two years.
The government will not normally follow you around or investigate your life beyond the required paperwork and the interviews it always conducts. But it has the power to look deeply into your life if the authorities get suspicious. Government inspectors can visit your home, talk to your friends, interview your employers, and more. By requiring more of married couples than others, the government has already set up a system that gives it a lot of information about whether your marriage is real.
What is the U.S. government's view of a normal marriage? The statutes and regulations don't go into detail on this, so the following comes from a combination of court cases and attorneys' experiences.
According to USCIS, the normal couple has a fair amount in common. They share a language and religion. They live together and do things together, like take vacations, celebrate important events or holidays, and have sex and children. Normal couples also combine financial and other aspects of their lives after marriage. They demonstrate their trust in one another by sharing bank and credit card accounts and ownership of property, such as cars and houses.
The government requires applicants to prove that they share their lives in a way similar to what is described above. Applicants do this by providing copies of documents like rental agreements, bank account statements, and children's birth certificates. The government further tests the validity of the marriage by talking to the applicant and usually to his or her spouse. Every marriage-based applicant for a visa or green card (including fiancés), whether they are applying in the United States or overseas, will have to attend a personal interview with a U.S. government official.
U.S. government officials have developed amazing talents for discovering fraud by examining what look like insignificant details of people's lives. To ferret out lies, they have learned to cross-check dates and facts within the application forms and between the application forms and people's testimony...