In the hyped-up political environment of the presidential election campaign, many of Obama's critics, unhappy with the administration's deportation of record numbers of immigrants found to be in the U.S. illegally, assert that, absent a major overhaul of the country's immigration policy and law, the president could use his executive authority — in this case, presidential pardons — to confer legal permanent resident status (a green card) – or some form of amnesty – on this segment of the country's population.
Undocumented or unauthorized presence in the United States is, however, a violation of civil law, and a president's power to grant pardons applies only to what the U.S. Constitution describes as "offenses against the United States" — i.e. federal or criminal offenses. Therefore a presidential pardon cannot grant someone citizenship or lawful resident status.
President Obama has tried to influence immigration policy by instructing Immigration and Customs Enforcement (ICE) to exercise what is called "prosecutorial discretion" when deciding which undocumented immigrants to detain for deportation, and also through a recently announced extension of this policy –DACA – Deferred Action for Childhood Arrivals.
In June 2011, John Morton, Director of ICE, published a memo instructing his agents to focus deportation efforts on undocumented immigrants found to have criminal records. On a case-by-case basis, ICE agents are instructed to consider factors such as whether the immigrant in question came to the U.S. as a child, "whether the person is a military veteran; has made 'contributions to the community'; acts as a caretaker of the infirm or disabled; or is very young, very old, pregnant, or nursing," as well as education and other factors.
The president's political opponents wail that this policy tweak amounts to a form of amnesty and that his policies do not address the fundamental underlying problem of comprehensive immigration reform.
In the meantime, it's best to remember that the myth that a sitting president can use his or her executive power to grant legal immigrant or citizenship status is precisely that – a myth.