Actually Matt, the Chief Justice (or the most senior justice in the majority if the Chief is in the minority) assigns the opinion. Believe me, that is an important power, the reason why Bush would never nominate Stevens as a sop to the left. Many times in history, the Chief Justice who would normally vote in the minority changes his vote to the majority and assigns himself the opinion so he can water down what the majority would normal set as law. Locke v. Davey is an example. If Rehnquist was in the minority, the liberals would have banned states from funding scholarships for students who want to study theology. Instead, the Chief wrote the decision stating that states can choose to fund them, or not. That is a huge difference.