“Whether the Harbor Maintenance Tax (HMT), 26 U.S.C. ยง 4461(a), as applied to goods loaded at United States ports for export, is an impermissible tax on exports or, instead, a legitimate user fee.”
“We hold, in accord with the Federal Circuit, that the tax, which is imposed on an ad valorem basis, is not a fair approximation of services, facilities, or benefits furnished to the exporters, and therefore does not qualify as a permissible user fee.”