"Of course income taxes are NOT unconstitutional. Except to those who don't actually know what is IN the constitution."
justshutupandtakeit, the only means by which the federal government could apply a tax was through interstate trade. A tax of 10% was to be levied to build and maintain a military for common defense.
All other powers to tax were relegated to the states, which at the time were more akin to individual countries, each governing its own.
That is not what is in the U.S. Constitution. Interstate trade was NEVER intended to be taxed. Nor was taxation restricted to funding national defense nor set at 10%. I have no idea where you got these looney tune ideas but certainly NOT from the Constitution. Article I, Section 8 clearly lists Congress's power to lay and collect "Taxes, Duties, Imposts and Excises...." and says that they may be used to provide for the common Defence and general Welfare. This is much more than just defence.
Adopting the Constitution took away much of the already limited sovereignty the states possessed (they never had real sovereignty.) And that was the intent of the convention. States have no sovereignty beyond that appropriate to actions affecting ONLY their own citizens. In fact, the Constitution lists a number of powers explicitly taken away from the states.
Contrary to the popular view around FR federal power was greatly EXPANDED by the constitution not limited and state power was significantly reduced. Advocates of that view need to carefully examine the campaign to call the Convention and the arguments against the Articles.