—Tetra Images—Getty ImagesWe were appointed to the federal bench by presidents of different parties. One of us was nominated by President Ronald Reagan; the other by President Bill Clinton. We have not agreed on every legal or political question. But on this Constitution Day, we agree on something more fundamental. We are worried about the health of the Constitution that we both swore an oath to support and defend. That is not a statement we make lightly.On Sept. 17, 1787, the delegates in Philadelphia signed a Constitution built around a simple but profound idea: Power in America would be divided. No president, Congress, court or political majority would control everything. Each branch would possess authority of its own, and each would constrain the others. The friction was intentional.Americans have argued over the boundaries of those powers since 1787. That argument is not a weakness of our constitutional system. It is part of the system. What concerns us today is something bigger than political differences. The guardrails surrounding our disagreements are weakening, and judges are paying the price. Judges are increasingly portrayed not as public servants applying the law, but as political combatants. Court decisions are too often treated as legitimate only when they produce the desired political result. Judges face calls for retaliation and removal because of their rulings. Threats against judges and their families remain at deeply troubling levels.That should alarm Americans of every political persuasion. A threat against a judge is not simply a workplace safety problem. It threatens the constitutional promise that cases will be decided neutrally according to law rather than fear.Judicial independence does not mean judges are above criticism. Court decisions should be scrutinized, debated, and sometimes sharply criticized. Judges make mistakes. Courts can get the law wrong.But our constitutional system provides ways to answer those decisions: appeal them, seek review by a higher court, change the law where Congress has authority to do so, or, in extraordinary circumstances, amend the Constitution.That is how a nation governed by law resolves disagreement. Threatening, harassing, or intimidating judges is something else entirely. So is teaching Americans that a court has authority only when its judgment favors their political side. The Constitution cannot function that way.Alexander Hamilton famously described the judiciary as the “least dangerous” branch because courts controlled neither the nation’s purse nor its military power. The judiciary ultimately depends on something more fragile: confidence in its legitimacy and the willingness of the other branches and the public to respect lawful judgments, even while challenging them through lawful means. That confidence is being severely strained.We understand why many Americans have concerns about the courts. Some question judicial ethics. Some believe particular judges or courts have become ideological. Others wonder why unelected judges with lifetime appointments should wield such authority.Those questions deserve serious discussion. Judicial independence is not immunity from accountability. Courts earn trust through integrity, transparency, ethical conduct, and fidelity to law. But there is a profound difference between holding the judiciary accountable and weakening its ability to perform its constitutional role.American history shows why that role matters. Courts have checked presidents of both parties. They have invalidated Acts of Congress and restrained state governments. They have protected fundamental rights. They have also made mistakes.The point is not that judges are always right. The point is that an independent institution exists where citizens can ask a basic question: What does the law require? That institution matters most when the answer is inconvenient to people who hold power. Our concern therefore extends beyond the courts.Constitutions do not usually fail because their words suddenly disappear. They weaken when the norms surrounding those words erode, when political advantage becomes more important than institutional restraint, when opponents become bitter enemies, when disagreement becomes grounds for retaliation, and when rules seem to matter only when they constrain the other side.No party is immune from that temptation. That is precisely why the Framers divided power in the first place. This Constitution Day should therefore be more than a commemoration of a document written nearly 240 years ago. It should be an examination of our own constitutional habits.Will we defend the independence of courts to neutrally and objectively decide cases even when we dislike their decisions? Will public officials lower the temperature rather than raise it? Will we reject threats against judges regardless of who appointed them? Will we accept that constitutional limits bind the leaders we support as surely as they bind those we oppose?After our many years on the federal bench, remaining silent about these questions would be easier. We do not believe it would be responsible.Sitting judges are appropriately limited in what they can say publicly. Those of us who have left the bench have both the freedom and, we believe, the responsibility to speak. The Constitution has endured not simply because its words are extraordinary, but because generations of Americans chose to honor its restraints. On this Constitution Day, that choice belongs to us again.