A primer on marriage fraud. Between 1998 and 2007 more than 2.3 million foreigners were granted permanent residence in the United States as spouses of U. S. citizens.
http://cis.org/marriagefraudMarriage to an American citizen remains the most common path to U.S. residency and/or citizenship for foreign nationals, with more than 2.3 million foreign nationals gaining lawful permanent resident (LPR) status in this manner between 1998 and 2007.
More than 25 percent of all green cards issued in 2007 were to the spouses of American citizens. In 2006 and 2007 there were nearly twice as many green cards issued to the spouses of American citizens than were issued for all employment-based immigration categories combined. The number of foreign nationals obtaining green cards based on marriage to an American has more than doubled since 1985, and has quintupled since 1970.
Despite these statistics, marriage fraud for the purpose of immigration gets very little notice or debate in the public arena and the State Department and Department of Homeland Security have nowhere near the resources needed to combat the problem. Attention to fraud is not just for the integrity of the legal immigration system, but also for security reasons. If small-time con artists and Third-World gold-diggers can obtain green cards with so little resistance, then surely terrorists can do (and have done) the same.
An overwhelming percentage of all petitions to bring foreign spouses or fiancés to the United States illegally (or to help them adjust visa status if they are already in the United States on non-immigrant visas) are approved — even in cases where the couple may only have met over the Internet, and may not even share a common language.