Rhyfelwyr, IANAL, but as I understand the legal reasoning it is thus:
  1. Prop 8 denies a state-sanctioned condition to a minority of the population (marriage and teh gayzorz)
  2. To make this denial valid, there must be a reason for it
  3. The defenders of Prop 8 claimed they were going to demonstrate 22 "specific" harms that gay marriage would cause the State of California (& citizens)
  4. They didn't articulate even one
  5. Hence the judicial/legalshut-out