The practice of marrying someone to help them get U.S. residency is nothing new, but what happens when that marriage ends in divorce?  That's the question being put to the test in a federal lawsuit filed against a Texas man by his Mexico-born ex-wife.  The woman is suing under a common but often-overlooked part of immigrant marriages called the "affidavit of support."  San Antonio-based immigration attorney Joseph B. De Mott says the idea behind the affidavit is to prevent immigrants from becoming a public drain.  "One of the requirements that's been in immigration law for a long time is that this person will not become a 'public charge' meaning they won't end up on welfare," he tells KTRH.

In order to assure the government that the new immigrant spouse won't become a "public charge," the U.S. citizen typically files the affidavit of support.  "It says you must provide the immigrant any support necessary to maintain him/her at an income that is at least 125 percent of the federal poverty guidelines," says De Mott.  However, the clause doesn't mention what happens in the case of divorce.  "Even if the marriage doesn't work out, that obligation to support the spouse that you emigrate is binding on the person," explains De Mott.  "You're on the hook until that person either becomes a citizen or they pay 10 years into social security."

PODCAST: Marrying an immigrant? "Affidavit of Support" details 'buyer beware'

In the Texas case, the ex-wife is demanding the man continue to support her under the affidavit of support.  De Mott says the case is unique because the affidavit is rarely enforced in divorce cases.  On the other hand, it is a legally binding contract.  "I've never heard of this kind of case being brought before, and I'm not sure how it's going to pan out," says De Mott.  The man being sued has reportedly called for this law to be clarified as part of the broader immigration reform.