Roberts wasn't playing politics, he was aiming for history

In making himself the fifth and deciding vote to uphold President Obama’s health-care reform (possibly changing his mind along the way), Roberts has shown himself a chief justice with a sense of history. By and large the chiefs who fare well down the years are the ones who prove effective politicians, men who understand that the Supreme Court is not a marble Brigadoon but a fundamentally political institution whose standing with the nation is fluid, not fixed.

(MORE: Roberts Rules: What the Health Care Decision Means for the Country)

John Marshall grasped this early on. Marshall is one of those Founders who remains more monumental than mortal — a fact that might surprise him and his contemporaries, for in real time the third chief justice established the principle of judicial review without forcing an existential showdown with presidents ranging from Thomas Jefferson to Andrew Jackson.