How do you check someone's claim that he was brought into the country illegally when he was a child? If Obama gets reelected, it is very unlikely that illegal immigrants will really have to prove anything. The administration can simply choose not to enforce that provision, as so many other immigration laws are unenforced in the Obama administration.
If Obama does not get reelected, then it may not matter anyway, when his Executive Order can be gone after he is gone.
Ultimately, it does not matter what immigration policy this country has, if it cannot control its own borders. Whoever wants to come, and who has the chutzpah, will come. And the fact that they come across the Mexican border does not mean that they are all Mexicans. They can just as easily be terrorists from the Middle East.
Only after the border is controlled can any immigration policy matter be seriously considered, and options weighed through the normal Constitutional process of Congressional hearings, debate and legislation, rather than by Presidential short-cuts.
Not only is border control fundamental, what is also fundamental is the principle that immigration policy does not exist to accommodate foreigners but to protect Americans -- and the American culture that has made this the world's richest, freest and most powerful nation for more than a century.
No nation can absorb unlimited numbers of people from another culture without jeopardizing its own culture. In the 19th and early 20th century, America could absorb millions of immigrants who came here to become Americans. But the situation is entirely different today, when group separatism, resentment and polarization are being promoted by both the education system and politicians.