At the conclusion of the American Revolution in 1783, the average human lifespan was about thirty-five years. The Framers, dissatisfied with the Articles of Confederation, convened the Constitutional Convention in Philadelphia, Pennsylvania, on May 25, 1787.
Article III of the resulting US Constitution provided judges of the "supreme and inferior Courts" with presumptive life tenure.Fast-forward more than two centuries. The average human lifespan in the United States is now over seventy-seven years. Due in part to the increase in longevity, the average term of years a Supreme Court Justice serves is steadily rising. On average, Supreme Court Justices now serve just over twenty-six years on the bench.