Once the Supreme Court interprets the Constitution on a specific point, the interpretation remains until the Constitution is amended or until the Court overturns a previous decision.
What is the likelihood of either of those actions? Should the courts have the power to make major policy decisions that are very difficult to change?

If the courts did not have such power, who would decide what policies or laws were constitutional or unconstitutional?
What would be the result of allowing Congress the power to determine what was constitutional?