Duty of tonnage

Definition and stakes

Joseph P. Bradley Parkersburg Ohio River Transp Company v…

But whether a charge imposed is a charge of wharfage or a duty of tonnage, must be determined by the terms of the ordinance or regulation which imposes it. They are not the same thing; a duty of tonnage is a charge for the privilege of entering, or trading, or lying in, a port or harbor; wharfage is a charge for the use of a wharf. Exorbitant wharfage may have a similar effect as a burden on commerce as a duty of tonnage has
Source: Wikisource

Portrait of Noah Haynes Swayne Noah Haynes Swayne Inman Steamship Company v. Tinker…

To one class of vessels it applies the rate here in question, to another class double that rate, and to yet another class none at all. Those belonging to the latter are wholly exempted.
We think a clearer case of the imposition of a tonnage duty than is presented in the record before us can hardly be imagined. If the law had been passed by Congress instead of the State, and the charge imposed had been expressly designated a tonnage duty, its character as such could not appear in a stronger light. But the name is immaterial: it is the substance we are to consider.
Source: Wikisource

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