Take a quick peek at the link info in post #26 here.
As to why it was made constitutional? Jealousy. The old excise system had a built-in bias against small farmers.
But they got the solution completely wrong just as Obamacare is completely wrong as a solution to Healthcare access and affordability problems.
The question I asked in my research is why if the FairTax is so awsomely superior and in conformance with the visions of the Founders, then why didn’t the Congress of 1913 pass a FairTax? The answer is spelled out in the latter half of the link in post #26.
Thanks Hostage! I thought I remembered something about this.