Like all other United States immigration laws, the Border Security, Economic Opportunity, and Immigration Modernization Act of 2013 will also deny adjustment to Registered Provision Immigrant (RPI) legal status if an alien (whether legal or illegal) ever made a claim to be an American citizen, and thus, gained benefits and privileges available only citizens. A huge number of illegal immigrants out of desperation or ignorance have repeatedly broken this law and there is an extensive paper trail documenting their criminal behavior.
How does the USCIS find out that a non-citizen made a fraudulent claim to be a US citizen?
First of all, the USCIS already knows that this crime is widespread, because every year so many undocumented aliens are prosecuted and thousands of immigration petitions are denied. The agents even know how the scheme works and they are extremely good at sniffing out who may have done so. However, like any other legal process, when you apply for adjustment to RPI status, you will also be asked a question if you have ever claimed to be a US citizen, and if you have done so, you have to tell the truth . By lying, you are risking not only chances of your legalization, you are also putting yourself at risk of being arrested, deported, and banned for life from entering the United States of America. Depending on the information you provide in your application, the USCIS can simply subpoena your file and that will contain a record of what you wrote and many workplaces will still have your I-9 forms, and they are required by law to comply (and most do willingly unless they are willing to pick a fight with Uncle Sam over the cost of the paperwork). Also remember that you will be swearing to tell the truth in your application and if you are found to be lying, your application will be rejected and you will be prosecuted.
What can I do if I made a claim to American citizenship but still want to become legal?
If an immigrant made the claim before the 18the birthday, then, this will not be a problem, and such aliens should confess their crime. If the claim was made (also) after the age of 18 but the applicant lacked the mental competence, she or he can still be forgiven, but the alien will be required to make that case before a judge and the judge will look into this more closely. Was it an innocent mistake that you thought you were an American because your parents told you a lie and you believed it or whether you knowingly made such claims over and over again even when you knew the reality so that you could get into college or get student aid or be able to work without the employer asking uncomfortable questions.
I don't think the USCIS can catch me because so many other illegal immigrants have not been caught:
This is a common refrain on forums frequented by undocumented aliens that they personally know individuals who were never caught by the USCIS even though they claimed to be US citizens or stole the identities of US citizens. However, as it might very well be the case, this is generally not a good assumption to make because you are putting your chance at legalization at risk. On the contrary, it is better to work with the hypothesis that you will be caught and find out legal remedies to mitigate the risk. In other words, hire the best attorney you can to discuss your legal options.