The revelation that Hillary Clinton used a private email address for most if not all of her official internal correspondence is raising all sorts of questions. According to widespread reporting, Mrs. Clinton turned over some 55,000 pages of emails to the State Department two months ago, long after she stepped down from her post in early 2013, and only after they were vetted by her loyalists.

One key issue getting a lot of ink is whether she violated the requirements of the Federal Records Act, which requires that official correspondence be retained as part of the agency’s record. But another far larger issue might loom.