I don't claim to be an expert, but a "sham marriage" could be sought by anyone who doesn't have legal status in the US.  The green card = permanent residency, and once obtained, few reasons anyone would lose it.  Other non-citizens might just have an H1B visa (worker), or student visa, or other type of visa (non-permanent status).  When those visas expire, individuals can find themselves in the "illegal" or "undocumented" status - and in desperate situations, that might make one seek out a sham marriage.

-----Original Message-----
From: Academy of Legal Studies in Business (ALSB) Talk [mailto:[log in to unmask]] On Behalf Of Ingulli, Elaine
Sent: Friday, February 17, 2012 10:11 AM
To: [log in to unmask]
Subject: Green card question

Does anyone know anything about immigration law?
I am making up a role play and want to create a role for a person on the cusp of being an "illegal immigrant"-- 
So: do Green Cards expire and have to be renewed? Is that what provokes "sham weddings"?

thanks
 Elaine Ingulli
Professor of Business Law
Richard Stockton College of New Jersey