At times, the Supreme Court will appoint a separate lawyer to answer a constitutional question that neither party wishes to defend. It is important that the Supreme Court answers every constitutional question here, and one of the major questions is whether the Supreme Court has the jurisdiction to decide this case given that the executive branch will not defend DOMA.
The fact that the Supreme Court appointed a separate lawyer to defend whether the Supreme Court has jurisdiction to rule in the DOMA challenge tells us NOTHING about how they will ultimately rule on the constitutionality of the DOMA. In fact, if Mrs. Jackson is successful, the court will not decide whether DOMA is unconstitutional. However, it is likely that they do decide.