http://www.slate.com/articles/news_and_politics/explainer/2012/06/aca_supreme_court_decision_how_do_the_justices_actually_write_their_opinions_.html
.......Unless this judge is Justice Antonin Scalia, who has often taken on the task of writing opinions himself, the judge will then usually select one of his or her clerks to take the first crack at drafting the opinion......