Is president Obama a constitutional scholar?

Yes, he is considered a scholar of Constitutional Law. In the academic world, a "scholar" is not just someone who has studied a subject and received an advanced degree; it is someone with considerable expertise and knowledge of that subject. Barack Obama received his law degree from Harvard Law School, where he was not only the editor of the Law Review, but he worked directly with a well-known expert in constitutional law, Professor Lawrence Tribe. Mr. Obama was also an adjunct professor of constitutional law for twelve years, at the University of Chicago Law School (they wanted to hire him full-time, but he had by then decided on a career in politics). Some people who ask this question disagree with the president on certain issues, so they may feel he is not applying the law the way they would like him to. But the fact remains that Mr. Obama has a long and well-documented history of studying, writing about, teaching, and researching constitutional law, so it would be fair to say he is a constitutional scholar.