The fact that Elena Kagan never served as a judge is being touted as an asset by her supporters -- but for the Senate Judiciary Committee members who need to vet her Supreme Court nomination, the lack of a paper trail makes their job that much harder.

The other eight justices on the Supreme Court all served on the bench at some point in their lives and came to Capitol Hill with a portfolio of opinions to present to the Senate before answering questions.

But Kagan has none of that. The material she submitted to the Senate Judiciary Committee last year for her solicitor general nomination covered about a dozen articles, including two book reviews. The rest of the background material was made up of e-mails and a slew of speeches and interviews she gave....