Supreme Court Fantasy League is a new fantasy league that allows you to compete against your friends, colleagues, and adversaries to determine who has the greatest ability to predict the outcome of Supreme Court cases.
The site is the brainchild of Josh Blackman, recent George Mason law grad and “big Supreme Court nerd.”
The Rules are simple, say the website:

For each case the Supreme Court grants cert, predict:
-The Outcome of the Case (Affirm or Reverse the lower Court)
-The Split (9-0, 8-1, 7-2, 6-3, 5-4, 4-1-4, or fragmented)
– The Justices in the Majority, and the Justices in the Dissent
At the end of the Term, the Associate Justice who predicts the most cases correctly will be confirmed as the Chief Justice of the Fantasy Supreme Court League, and win a to-be-determined prize.
Update: By popular demand, I am currently developing a League feature. Soon, users will be able to join leagues for schools, law firms, and other groups. Stay tuned.
Now you can play like the Tenth Justice.

Source: Marquette University Law School Faculty Blog See also WSJ Law blog