With the retirement of Justice Kennedy, there has been a lot of talk about the Supreme Court and the fact that it will likely become a radically conservative body and that Democrats will be unlikely to reverse that for many years. However even outside of our current moment, the structure of the supreme court has been deeply flawed and prone to becoming taken over by partisans and then failing to respond to democracy.
5 supreme court justices protected by just 34 US senators can literally strike down any law passed by Congress and signed by the president. Obviously, they are only supposed to strike down laws that are unconstitutional, but the only check on their power is impeachment which requires two-thirds of the Senate meaning that currently you just need 34 senators to block an impeachment.
The problem is that there are clearly ways to interpret the constitution that push a political agenda. This means that when hardcore partisans make up the Senate and the presidency have every reason to find and push justices who will promote their agendas from the bench. It is somewhat acceptable for partisans to make up the halls of Congress and the presidency (although even here there is clearly a limit). The reason this is acceptable is that these branches of government are relatively responsive to democracy meaning that if people are displeased with the direction they are going they will have a chance to vote them out in a few years. The Supreme Court, on the other hand, doesn’t change every election cycle and even if one party retakes and holds both the White House and the Senate for many years it can be a long time before they get to replace enough justices to swing the court back to their partisan bent. The reality is that the court either needs to be more responsive to democracy or to be more shielded from partisanship.
One method that has been used to shield the court from partisanship is a super-majority requirement to justices appointed to the supreme court. Requiring either ⅗ or even ⅔ of senators to vote to confirm. This would mean that the president would have to appoint someone tolerably to both political parties and the presence of the filibuster until 2017 effectively added this moderating pressure though it was always unstable do to the ability of a simple majority to remove the filibuster. The big problem with this is that if parties continue to grow more partisan and engage in more constitutional hardball it could leave one in a situation where it is impossible to confirm someone to the US Supreme Court and it slowly hollows out as it becomes impossible for a president to nominate someone acceptable to both sides.
Another option, that was originally proposed by Rick Perry, is to implement nonrenewable term limits of 18 years and to stagger them so that every president appoints 2 Supreme Court Justices per term. This would still preserve the independence of Supreme Court Nominees as they would not have to stand for election and since they would be banned from serving more than 1 term they would have no incentive to please the party/president that appointed them and would be free to rule as they see fit. Additionally, due to the lengthening in humans lifespans, the average tenure of a member of the supreme court has stretched to out enormously. It used to be far less common to have justices serve for 30 and 40 years periods on the Court. The 18 years term would not only limit the influence of a single Justice but it would mean that the court would be more responsive to democratic changes but that it would not rapidly flip back and forth either.