We develop a positive political model of the U.S. Supreme Court. Looking at the Court's economic cases for the period 1953-1993, we find a significant larger fraction of conservative decisions under Republican presidents and more conservative leadership of the House and Senate Judiciary Committees. Conservative decisions are also found to be positively correlated with the fraction of the Court appointed by Republican presidents and the rate of price inflation. We argue that our findings cast serious doubt on the common view of the Supreme Court as a completely independent, apolitical institution.