Benjamin N. Cardozo,
Hale v. Iowa State Board of Assessment and Review…
“ Nor do I see any ground for confining it to taxes then known to the Iowa law. Such an all-embracing exemption cannot be avoided by the invention of a new tax. To me, it seems evident that, if any tax be imposed upon the bonds, the contract is impaired. It likewise seems evident that the tax here is imposed on the bonds themselves.Of what does a bond for the payment of money consist? Certainly not the principal alone; for the promise to pay interest is as much a part of the obligation of the bond as the promise to pay the principal. ”
