Recent cases, the ACA and the voting controversy in Florida regarding votes cast for the POTUS, that went in front of the Supreme Court shows that they are political rather than apolitical and impartial. Their tenure protects their lack of impartiality.
Term limits, same as the POTUS, should be imposed on all supreme court justices. The highest court in the land must be impartial and objective and must provide opinions based on the law and the constitution and not on political affiliations, agendas or personal beliefs. Life tenure encourages political decisions and lacks accountability. Term limits makes them accountable to the people for their decisions and their lack of impartiality.