The downfall came with the idea that the Constitution is a "living document" that should be constantly changing by it's interpretation. That method of change isn't included in the document and is itself inherently unconstitutional. It offers two very specific methods for changing it and neither gives that power to the court system.
But how could you make needed changes in the current political environment? The highly charged polarization between the Democrats and Republican parties makes changing the menu in the congressional cafeteria almost impossible. We elect people to go to Washington to represent an area of the country, not a political party. The system was designed so that the most liberal and the most conservative representatives should be able to join together in legislation that would benefit both their areas. That doesn't happen in the midst of the ongoing partisan war in Washington.
My idea for the solution is a nation of independent voters. Select your candidate by the person most capable of doing the job regardless of party. Donate directly to the candidate if you want but don't donate a dime to either party. Throw their trash-the-opponent literature in the garbage and make partisanship a negative in the voting booth.
If we can get back to a solutions based political system rather than the current power and access struggle, then we might be able to call another constitutional convention and make the Constitution mean what it says. Until we can elect people who represent the country instead of parties, this quagmire will only deepen.