A complaint has been filed against him with the Illinois State Bar
http://amerpundit.com/2008/07/24/complaint-filed-against-obama-with-the-illinois-bar/
Obama was admitted to the Illinois State Bar in 1991
Under status it says:
Voluntarily inactive and not authorized to practice law - Last Registered Year: 2008
All he has to do is reactivate his license as per Illinois law. They probably have a inactive fee that he has to pay every year versus the fee that he would have to pay if his license was active.
It isn’t lapsed as in he would have to retake the bar exam.
It is just inactive.