I am afraid you don't understand that either. Our government has three coequal branches, Executive, Legislative, and Judiciary with a series of checks and balances to keep any one from becoming all powerful. Supreme Court Justices can be impeached by the Congress. Their rulings can be overturned by acts of Congress. The Executive can ignore them. The entire court can be eliminated by a constitutional amendment.
The idea that the court's rulings can't be overturned because they become precedent is a myth pushed by the left to keep their unconstitutional court rulings in place.
Under what circumstances? As to impeachment, that is limited to treason and criminal activity.