I would argue that progressive taxation is unconstitutional because, going back to Corfield v Coryell it is clearly stated that among out Privileges and Immunities — the other rights retained in the 9th Amendment — is to not tax different persons differently … and your income isn’t paying the tax … you are!
And while an argument may be made on account of the soak the super rich diatribe that was part of the arguments for the 16th Amendment, and which could be said to have established its intent, that still means that progressive income taxes for everyone who isn’t in that inflation adjusted group should be simply gone. And as for any form of progressive taxation beside the income tax, or and State taxation, Corfield should be seen as forbiding all efforts at progressive taxation which inherently tax some persons differently than others.
BOR? Constitution? LOLOL! Written by a bunch of old white slave owning dudes centuries ago. No longer relevant. As brandon reminded us, those rights aren’t absolute. Like the 13th and 19th amendment. Try steppin’ on those.