THE PHRASE “checks and balances” does not appear anywhere in the United States constitution; and yet in a manual for Martians on how America governs itself it would be on page one. Those three words are a reminder that the country has an unwritten constitution, which resides in beliefs, behaviour and legal precedents, to go alongside its more celebrated written constitution. They describe how the branches of government compete for power—a contest where, the founding fathers wrote, “Ambition must be made to counteract ambition.” The question for the Supreme Court’s new term, which starts next week, is: how much ambition do the justices have?
