Separate appeals courts this week vacated legal victories that the federal government achieved in the aftermath of the financial crisis. The cases involve former officials at State Street Bank and Trust and a former MBS trader at Jefferies & Company. In 2014, commissioners of the Securities and Exchange Commission voted 3-2 to reverse a ruling by the SEC’s Chief Administrative Law Judge involving James Hopkins, a former vice president and head of North American product engineering at State Street, and John Flannery, a former CIO at the bank. The ALJ had dismissed...