I should have written 13-25 justices. The primary ideas being that (1) justices have term limits and (2) each Presidential 4-year term appoints the same number of justices, barring a death or resignation.why 25 justices? do you want them all to hear each case, or are you envisioning something like an appeals court where there's a panel of justices selected from the larger pool.
I'm not a fan of either idea. 25 justices would be unwieldy, and since they love to write concurrences and dissents, the opinions would become ridiculously long. Oral arguments would be hell.
If you went with the panel approach, then there will be a lot of randomness like in appeals courts, where cases are often decided basically by the random dice roll that determines which judges are on which panel.
If it’s to be 25 justices, yes they’d meet as a sub-panel. It would be possible to appeal the sub-panel’s decision to the entire Supreme Court (obviously, it doesn’t have to hear the appeal).
I like your idea of 18-year terms with each term ending on a rotating 2-year basis. The only thing I don’t like about that is we still have 9 justices - that likely locks in the right-wing majority for another 10-20 years.