The more we learn about the Justice Department’s investigation of Hillary Clinton’s private email, the worse it looks. The latest revelation is that, along with granting immunity to two Clinton aides, Justice agreed to secret side deals that provided highly unusual protections from potential prosecution.

The side agreements came to light this week in a letter from House Judiciary Chairman Bob Goodlatte to Attorney General Loretta Lynch. Mr. Goodlatte says he learned about the side deals by examining the immunity agreements,...