Last week, I wrote an article describing several purchase mandates adopted by the framers in early Congresses, including two medical insurance mandates imposed on shipowners and seamen. These examples rebut the claim by challengers to Obamacare that purchase mandates are wholly unprecedented in a way that allows us to infer they are unconstitutional, a claim on which they rely heavily because there is no text, history, or case law that affirmatively supports a ban on purchase mandates.

Not everyone agrees with me. Some comments to my article, here and elsewhere, have suggested that these early medical mandates are distinguishable from Obamacare because they reflect Congress’ power to enact maritime law, not its power to regulate commerce. But the Constitution’s list of congressional powers nowhere includes a maritime law clause. Early Supreme Court cases all held that the Commerce Clause was what gives Congress the power to enact maritime law. For example, in The Daniel Ball, a case decided in 1871, the Court stated that navigable waters form “a continued highway for commerce, both with other States and with foreign countries, and is thus brought under the direct control of Congress in the exercise of its commercial power. That power authorizes all appropriate legislation for the protection or advancement of either interstate or foreign commerce…” In The Lottawanna, the Court held that it was under this commerce clause power that Congress had enacted statutes that determined “the rights and duties of seamen” and “the limitations of the responsibility of shipowners.” These early medical mandates were thus enacted under the very Commerce Clause at issue in the Obamacare case.

To be sure, later cases have held that Congress also has power to modify any judicial maritime common law, reasoning that this Congressional power is necessary and proper to regulate the judicial power to decide maritime cases. But these later cases do not alter the fact that the early federal maritime statutes were based on the Commerce Clause. Nor do these insurance mandates seem to fit within this additional power to alter maritime common law, which was about adjudicating disputes rather than imposing affirmative regulatory duties. Even if the mandates did fit, that would simply show that such mandates were “proper” under the necessary and proper clause.

Others—including the intellectual architect of the challenge to Obamacare, Randy Barnett— acknowledge that our early maritime statutes exercised the commerce power, but distinguish them on the ground that they were imposed on actors who were already in commerce. But this argument concedes that these precedents show that if one is engaged in commerce in one market, such as the shipping market or the seamen labor market, then Congress has the power to impose a mandate to purchase in a totally unrelated market—such as the medical insurance market. This concession conflicts with the argument of Obamacare’s challengers, who claimed that widespread activity in the health care market did not permit a purchase mandate even in the highly related health insurance market. Indeed, this concession seems to make the whole action/inaction distinction collapse: If no relation between the markets is required, then commercial activity in any market would permit the Obamacare mandate. Because the Obamacare mandate applies only to those who have significant income that subjects them to income tax, it is necessarily limited to people who are already active in some commercial market. You cannot earn income without engaging in commerce. Thus, Obamacare satisfies the test that Barnett himself derives from these precedents. 

Finally, some argue that the 1798 law requiring seamen to buy hospital insurance was a tax rather than a mandate. But the “duty” automatically deducted from seamen’s wages under this law was not a general tax: The collected funds were segregated and had to be used to provide hospital coverage in the districts in which they were collected. This sort of mandatory payment into a segregated fund is indistinguishable functionally from a requirement to participate in a local hospital insurance pool. True, this statute did not require the seamen to provide proof of payment in order to receive hospital care. But the automatic nature of the deduction meant that proving one was a seaman was proof enough of payment. Nor does this argument distinguish Obamacare: Individuals currently do not have to provide any proof of payment in order to receive emergency hospital care, and part of the purpose of the Obamacare mandate was precisely to fund such emergency care. In any event, the intrusion on free market choices is identical, whether we call the required payment a mandate or an earmarked tax.

Einer Elhauge is a professor at Harvard Law School. He joined an amicus brief supporting the constitutionality of the mandate.