(NECN: Peter Howe, Boston) - After Congress refused to accept the changes when it rejected the DREAM Act, President Barack Obama unilaterally implemented a temporary deportation reprieve for undocumented immigrants Wednesday.

The reprieve is one that could transform the lives of up to 1.7 million people, but one some experts say affected immigrants could well be leery of signing up for.

The policy affects people under the age of 31 who were brought to this country as undocumented immigrants before they were 16, and have lived her continuously for at least five years. If they are in high school or are high-school graduates, or serving in the military or honorably-discharged veterans, and have no significant criminal convictions, they can apply to the U.S. Citizenship and Immigration Services to be awarded a two-year respite from the threat of deportation. This will allow people who now, technically, could be deported any day – even though they were children when first brought into the country illegally, typically by parents or relatives – to sign up to work legally or get a professional license or join a union. The policy is officially called Deferred Action for Childhood Arrivals.

"For the very first time, I have the prospect of working legitimately, which means a number of things," said Carlos Rojas, 18, of East Boston. "It means that I'll be able to save up money for college, earn money to help my family."

Carlos was 5 years old when rebels in war- and drug-infested Colombia killed his uncle, prompting his anxious family to flee to the U.S. on a six-month tourist visa. They stayed, in violation of immigration laws, and Carlos has grown up to be a model immigrant, a June graduate of the prestigious public Boston Latin School, lover of the Boston Red Sox and politics and dramatic productions at school – and, theoretically, at constant risk of being sent on a one-way ticket back to Colombia.

"It’s not a daily fear, but it is something that affects the way you look at life and the way you look at things, just knowing that any little thing could get me deported, any little interaction with law enforcement," Rojas said.

And it’s severely crimped his ability to do typical American teenager things like get a job or a driver’s license.

"It bummed me out, because I wasn’t able to do that," he said.

Boston immigration lawyer Berin Romagnolo of Posternak, Blankstein & Lund says immigrants covered by the DACA amnesty should be "optimistically cautious" about taking advantage of it. While it confers significant benefits, such as being able to get jobs other than under-the-table work, or student loans or driver’s licenses or other benefits, Romagnolo said she can see many reasons why immigrants who’ve managed to stay off the government’s immigration-enforcement radar would be leery.

"In two years, if it's not extended, they are on the radar for being deported, and their family's on the radar for being deported," Romagnolo said.

CIS, the bureaucracy that processes citizenship requests, has publicly promised it will not share information that comes in through the DACA program with Immigrations and Customs Enforcement (ICE), the police agency that has tracked down and deported over 1 million undocumented immigrants in the last four years.

But, Romagnolo said, it’s easy to imagine why immigrants who fled from countries where people have strong reasons not to trust the government might be less than confident the U.S. government won’t go back on that promise – particularly if Republicans Mitt Romney and Paul Ryan defeat President Obama and Vice President Joe Biden in November. Romney has opposed the Obama DACA executive order but urged comprehensive immigration reform.

For employers, the DACA deportation reprieve is also problematic, Romagnolo said. If the policy ends in 2014, at that point employers would have to fire any temporarily-amnestied workers they had employed and replace them with citizens.

"If they don't, then they are in danger for all the penalties that come along with employing an illegal worker. A lot of them are monetary, but there's also imprisonment," Romagnolo said, and any situation with one worker could lead to ICE asking for a host of records from an employer that could reveal an employer has other undocumented workers on staff.

On balance, the Massachusetts Immigrant and Refugee Advocacy Coalition is telling those affected that the rewards of seeking a DACA deportation reprieve clearly exceed any risks, and is organizing events in communities like Chelsea, East Boston, Lawrence, Lynn and New Bedford that are home to many affected immigrants to help them learn how to file. The coalition estimates about 10,000 to 20,000 people in Massachusetts could qualify.

But, MIRA communications director Frank Soults said, "This has to be the first step in continuing to advocate and to lobby for real political change, real permanent change, and change in the law."

For Carlos Rojas, it all comes down to whether he can legally work and study in the nation he loves and has called his own since he was five.

"I think I’m really like a typical American kid," Rojas said. "I love movies. I love hanging out with friends. I love watching the Red Sox … Thirteen years later, this is my life. This is really my country."

With videographer David Jacobs.