[Verginius Rufus]

I don’t know if Obama was the first black to be on the law review period. He was the first to be “president” of the law review, which hitherto had gone to the top law student. The time had come, they decided, that they had to have a black president of the law review, and he was the top student among that subset. Apparently as president he didn’t do the work traditionally done by the president but let his underlings do that.

[TexasFreeper2009]

Your correct, he was the first black president of the Harvard law review, which had historically always gone to the top student, but because no blacks could earn the top spot they instituted an affirmation action program to ensure a black that hadn't earned it got the spot, and Obama just happened to be the first beneficiary of the new system.