See here. The government had claimed the ruling under the Speech or Debate Clause made lawmakers invulnerable to prosecution for corruption.
The Court also agreed to hear a case involving an Idaho law on political dues. Lyle Denniston explains: “The other granted case, Ysura v. Pocatello Education Association (07-869), tests a Ninth Circuit Court ruling that the First Amendment bars the Idaho legislature from denying payroll deductions by local governments for political activities. The Idaho law at issue barred payroll deductions to pay for political activities by labor unions. The law was challenged by labor unions representing workers for school districts, cities and counties in Idaho.”