http://www.uscis.gov/USCI...0Guide/U.S._Citizens.pdf

**This is how the law read(from 1952-86) at the time of Obama's birth--Milt

In general, you may have been a U.S. citizen at birth if:
• Before you were born, the citizen parent had already lived (been physically present) in the United States for at least 10 years and at least 5 of which were after the parent turned 14.
• Periods of the parent’s honorable U.S. military service, employment with the U.S. government or with certain international organizations, or residence with a parent so employed may count towards the physical presence requirement.
If your U.S. citizen parent doesn’t have the required residence or physical presence in the United States before you were born, then you did not automatically derive citizenship at birth from your parent.