Mr. Jiménez’s benchmark case exposes a little-known but apparently widespread practice. Many American hospitals are taking it upon themselves to repatriate seriously injured or ill immigrants because they cannot find nursing homes willing to accept them without insurance. Medicaid does not cover long-term care for illegal immigrants, or for newly arrived legal immigrants, creating a quandary for hospitals, which are obligated by federal regulation to arrange post-hospital care for patients who need it.

American immigration authorities play no role in these private repatriations, carried out by ambulance, air ambulance and commercial plane. Most hospitals say that they do not conduct cross-border transfers until patients are medically stable and that they arrange to deliver them into a physician’s care in their homeland. But the hospitals are operating in a void, without governmental assistance or oversight, leaving ample room for legal and ethical transgressions on both sides of the border.

Indeed, some advocates for immigrants see these repatriations as a kind of international patient dumping, with ambulances taking patients in the wrong direction, away from first-world hospitals to less-adequate care, if any.

“Repatriation is pretty much a death sentence in some of these cases,” said Dr. Steven Larson, an expert on migrant health and an emergency room physician at the Hospital of the University of Pennsylvania. “I’ve seen patients bundled onto the plane and out of the country, and once that person is out of sight, he’s out of mind.”

Using the Current Population Survey by the Census Bureau as the quantitative basis for their report, CIS notes that "since hitting a peak in the summer of 2007, the illegal population may have declined by 11 percent through May of 2008."

This data leads them to conclude that "it seems that increased enforcement is at least partly responsible for this decline."

However, Stephen Buckner, a spokesman for the US Census responded to this report by saying: "The Census Bureau does not produce estimates or counts of illegal immigrants living in the United States."

Additionally, the Immigration Policy Center (IPC) took issue with the report. "The persuasiveness of CIS' argument is undermined not only by an absence of hard data, but by the faulty logic and contradictory statements of the report itself" and added "the authors report confidently about a population that is nearly impossible to accurately measure."

In addition, IPC took exception with CIS' conclusion that immigrants are leaving because of stepped-up immigration enforcement. If there is indeed movement, IPC contends, something that has not yet been proven, then it's likely more because of economic conditions rather than immigration-enforcement measures, as has been the case historically.

PARTICIPATING CITIES: Chicago; Santa Ana, Calif.; San Diego; Phoenix and Charlotte, N.C.

WHO QUALIFIES FOR THE PROGRAM? Immigrants who have ignored deportation orders to leave the U.S. and do not have a criminal history. Federal Immigration officials estimate 457,000 are eligible nationwide.

HOW LONG WILL THE PROGRAM RUN? It started Tuesday and runs through Aug. 22.

WHERE DO PARTICIPANTS REPORT? Local ICE offices. Individuals are asked to bring whatever form of identification they have, such as an expired passport. A hot line is also available for more information: 1-866-880-6344

(Ken Carlos, ICE official:) "They're able to come in to avoid detention because they're going to come in and they're working with ICE. They're going to be able to work with their families to make arrangements to go home so it's not where all of a sudden theres a knock on the door and they're being arrested."

Carlson says it isn't clear how many people might take advantage of the program between now and the August 22 deadline.

But immigration rights advocates say it won't be many.Fred Tsao is policy director for the Illinois Coalition for Immigrant and Refugee Rights. He says the program offers no incentives for fugitives to surrender to ICE, rather than just leave the country on their own.

• "There was no simple right versus wrong here. Rather than deal with the conflict, we too often gloss over the surface by advocating that we “do the right thing” regarding financial costs but turn our backs on our own compassionate feelings by compelling the illegal immigrant to leave the United States to get medical assistance back home, in this case in Guatemala, knowing full well that proper medical assistance is not available in Guatemala."
• "Your article did not convince me that the hospitals are behaving badly. The brutal truth is that allowing unregulated millions of illegal immigrants into the country can only result in the destruction of American institutions such as hospitals and schools."
• "What is the moral mandate for a Florida acute-care hospital that has already spent $1.5 million of its own money caring for a foreign citizen to also provide him with long-term care?"