As Weekly Standard notes, Obama lied regarding his motivation for voting against the Illinois born alive infant protection act:
Questioned about his vote against the born-alive infants protection act, Obama said: “There was already a law on the books that required lifesaving treatment, which is why … I voted against it.” Obama and his colleagues never cited this law as a reason for opposing the bill in the Illinois Senate. More importantly, that 1975 law only protected “viable” infants–and left the determination of viability up to the abortionist who had just failed to kill the baby in utero.
The National Right to Life have done their homework on this subject — see Barack Obama’s Actions and Shifting Claims on the Protection of Born-Alive Aborted Infants -– and What They Tell Us About His Thinking on Abortion for short rebuttals to a number of Obama’s perpetually-shifting claims about why he sought to suppress this legislation in 2001, 2002, and 2003 while an Illinois State Senator. For much more extensive documentation on the Obama record on this issue, see Index of documents relating to Barack Obama and the Born-Alive Infants Protection Act.