This 9th circuit case, Silveira v. Lockyer, involved private plaintiffs challenging a state law (hence AG Lockyer as the defendant) on federal grounds. Now that plaintiffs have lost their appeal, how does the Justice Dept step in and appeal it to SCOTUS? The Justice Dept was never involved.
If the plaintiffs now petition the SCOTUS for certiorari, the Justice Dept can file an amicus brief with the court in support of that petition.