Last time I got a passport, I needed a BC.
Did you need a real one, or do you think you could have gotten by with a forged one?
If you didn't have a BC, the State Department would have accepted other forms of identification.
from the State Department Website:
"Secondary Evidence of U.S. Citizenship
If you cannot present primary evidence of U.S. citizenship, you must submit secondary evidence of U.S. citizenship. Determine what form of secondary evidence is most appropriate for your situation based on the descriptions below. Each application is handled on a case-by-case basis. The scenarios below are intended as general guidance.
# Baptismal certificate
# Hospital birth certificate
# Census record
# Early school record
# Family bible record
# Doctor's record of post-natal care
Or
Letter of No Record
If you were born in the United States and cannot present primary evidence of U.S. citizenship because you do not have a previous U.S. passport or a certified U.S. birth certificate of any kind, you must present a state-issued Letter of No Record showing:
-snip-
And
Delayed Birth Certificate
If you were born in the United States and cannot present primary evidence of U.S. citizenship because your U.S. Birth Certificate was not filed within the first year of your birth, you may submit a Delayed U.S. Birth Certificate. A Delayed U.S. Birth Certificate filed more than one year after your birth may be acceptable if:
check image It lists the documentation used to create it (preferably early public records) and check image It is signed by the birth attendant or lists an affidavit signed by the parents
Letter of No Record
If you were born in the United States and cannot present primary evidence of U.S. citizenship because you do not have a previous U.S. passport or a certified U.S. birth certificate of any kind, you must present a state-issued Letter of No Record showing:
check image Your name
check image Your date of birth
check image The years for which a birth record was searched
check image Acknowledgement that no birth certificate was found on file
Form DS-10: Birth Affidavit
-snip-
Foreign Birth Documnts + Parent(s) Citizenship" Evidence"
-snip-
http://travel.state.gov/passport/get/Secondary%20Evidence/Secondary%20Evidence_4315.html
As you see they're are plenty of ways to get a passport and opportunities to game the system, which Obama may have taken advantage..