WASHINGTON, Aug. 2, 2010— -- Like most 20-year-olds these days, Max admits he wasn't quite ready to get married when he wed Maria on a South Florida beach in March, never mind to someone he'd been dating for only four months.
But the undocumented Argentine immigrant -- who asked ABC not to use his real name -- said he couldn't turn down Maria's proposal, especially since it could offer him the chance to become a U.S. citizen alongside his love.
"We talked about if we choose to stay together it would be easier for me to have some status," Max said. By law, Maria, 22, a U.S. citizen, can sponsor her spouse for a visa to live in the country legally.
Last year 227,000 foreign nationals obtained green cards through marriage -- more than any other category of applicant, according to the U.S. Citizenship and Immigration Service. And the numbers are on the rise: up 56 percent from three years before.
Still, many couples with a foreign spouse say marriage is not the easy or automatic path to legal U.S. residency it may seem, citing authorities' intensive efforts to ferret out phony marriages through interviews and investigations.
The process is sufficiently intimidating to Max and Maria that the couple has still not filed the paperwork for a green card, four months after getting married and despite confidence their marriage would pass the test.
Immigration officers scrutinize each couple that applies for a spousal green card, conducting criminal background checks, multiple individual interviews and often visits to the couple's home. The goal, officials say, is to detect disparities between information provided on the application and reality.
"It's an anxiety in the back of my head," Max said of the process. "It's the fear that your life could completely change at the hands of a couple (of) people. ... It could be completely destroyed in a matter of seconds by some guy or woman in uniform, at a desk."
If the couple filed the petition and it was denied, Max said, he would be at heightened risk of detention and deportation.
Feds Investigate Sham Marriages
"We might ask about the number of bedrooms in their house, their dog's name or whether they even have a dog, what color toothbrush their spouse uses," said U.S. Citizenship and Immigration Services spokeswoman Chris Rhatigan of the agency's effort to uncover scams. "We'll also go to the address they give us to see that they actually live there."
The agency uncovered and denied more than 600 fraudulent green card applications for foreign spouses between 2007 and 2009, according to the most recent statistics.
Rhatigan said some of the offenders were turned over to Immigration and Customs Enforcement authorities for prosecution, with both husbands and wives facing up to five years in prison and a $250,000 fine for trying to evade federal law.
The number of sham marriages is small compared with the more than 700,000 residency petitions by foreign spouses the Citizenship and Immigration Service received in the same three-year period, and the nearly 40,000 petitions "ended, terminated or withdrawn" for reasons other than fraud.
But some experts say the mere existence of fraud is making the process more difficult for legitimate couples such as Max and Maria, leading to longer wait times and more invasive investigations by immigration officials.
"The numerous arrests of those involved in marriage fraud schemes and the hundreds, if not thousands, of websites that exist solely for the purpose of arranging scam marriages, all indicate that marriage fraud is a serious problem," David Seminara, a former consular officer with the Center for Immigration Studies, wrote in a recent report.
For now, Max, a college student with plans to study engineering in the Ivy League, says he's content just legally married in Florida. Filing the immigration petition can come later, when he and Maria reach a point in their lives to handle an investigation and what they expect will be a hefty legal bill for the process.
"We are not the marriage police," said Rhatigan. "And we are sensitive to different cultures and different customs... Legitimate couples have no reason to be afraid."
More stories from ABC News' special series "Out of the Shadows: Illegal Immigration in America"