“In good behavior”, with accountability to Congress.
De facto for life with no accountability is, like many problems in the US system of government, largely a side effect of the combination of defective electoral system and the resulting norm of near-balanced partisan duopoly, which in the case of the judiciary combines with the supermajority requirement for conviction on impeachment charges to achieve lack of accountability; the same is also true of the executive, though finite terms, electoral accountability, and in principal (and currently being tested in practice) post-term legal accountability are arguably mitigations there.
Their ability to interpret rights and issues is checked by Congress actually passing specific legislation on those issues, or even better constitutional amendments.
They are also directly accountable in terms of confirmation and impeachment.
The seeming rise in power of the Supreme Court is in some ways a long tail symptom of the continuing lack of efficacy of Congress to fulfill their duties as lawmakers and proportional representatives of the citizens they serve.
Yes, we do. However, regardless of what the system intended, that's not what we have anyway.
But this is a political problem. What non-political solutions are even possible?
https://en.wikipedia.org/wiki/Supreme_Court_of_Justice_of_th...
it would take a lot of collective effort to make it happen, though.