As a border and protection officer, I'l assume, you had to apply for the job. In that flurry of paperwork, did you see a I-9 form, currently the DHS I-9 form?
http://uscis.gov/graphics/formsfee/forms/i-9.htm
Take the time to read page #1 Instructions carefully, then fill in section #1 and sign your name.
Next look at page #3 and see if you have any documents listed in column "A". If you have at least one document listed in column "A", STOP, you are eligible for employment, in the USA. If NO continue.
Do you have one document listed in column "B"?
If NO STOP, you are not eligible for employment in the USA.
If YES, continue to column "C".
Do you have one document listed in column "C"?
If YES, continue to column "C". Youare eleigible for employment, in the USA.
If not, then by golly, you must be an illegal alien.
Please note the following changes to the Form I-9 process:
Form I-766 (Employment Authorization Document), although not listed on the 5/31/05 version of the Form I-9, is an acceptable List A document #10.
Form I-151 is no longer an acceptable List A document #5. However, Form I-551 remains an acceptable List A document #5.
The following documents have been removed from the list of acceptable identity and work authorization documents: Certificate of U.S. Citizenship (List A #2), Certificate of Naturalization (List A #3), Unexpired Reentry Permit (List A #8) and Unexpired Refugee Travel Document (List A #9).