If implemented, the tariffs announced yesterday by President Trump would constitute the largest tax increase since the 1968 levies to fund the Vietnam War.

The details will matter, but my back-of-the-envelope calculation suggests that the tariffs — which are taxes on imported goods — could be as large as 2 percent of annual GDP. This tax increase would be larger than the expiring 2017 tax cuts that Trump is trying to extend.

For the president to attempt to unilaterally raise taxes by hundreds of billions of dollars per year is an aggressive and egregious assault on our constitutional system of government. In the Constitution, it is Congress’s role to raise revenue, not the president’s.

I am an economist, not a constitutional scholar. I don’t know whether Trump is violating the Constitution in a technical legal sense. But I am a citizen of the United States, and I know that Trump is violating the spirit of the Constitution. The president raising this much revenue through import taxes without authorization from Congress is an obvious and extreme abuse of power.

And for what? From my Financial Times column:

Vice President JD Vance argues that Trump “believes in economic self-sufficiency.” Well. To see the benefits of economic self-sufficiency, look to North Korea. Still, Vance is right. Trump is a true mercantilist who views trade deficits with hostility.

The goal of eliminating the trade deficit is wrongheaded, as I argue in a recent paper for the Aspen Economic Strategy Group:

First, [Trump] misunderstands the ultimate cause of the trade deficit. The US trade deficit is not driven by foreign governments blocking US exports or subsidizing their own exports. Instead, the trade deficit is driven by the savings and investment decisions of American households and businesses and by the taxing and spending decisions of the US government.

The US spends more than it produces. The US invests more than it can finance through national savings. Simple national income accounting demonstrates that this state of affairs requires that the US also run a trade deficit. Trade policy can affect bilateral trade flows, but it cannot counter these broad macroeconomic aggregates.

The second reason: If your goal is to reduce the trade deficit, then your goal must also be reducing flows of foreign investment into the United States. When the US consumes and invests more than it produces, it must be running a current account deficit. To finance the deficit, the US sells assets to the rest of the world, and capital flows into the US from abroad.

It is also helpful to consider an intertemporal context. Today, the US wants to invest more than it saves, so it must attract foreign capital. For that foreign capital to exist, the rest of the world must be saving some of its output and income. So, some of the output of foreign nations flows into US markets.

Foreign direct and portfolio investments are votes of confidence from other nations in the US economy and, more broadly, in the United States as a whole. These investments make workers more productive—increasing their wages and incomes—and make US firms more competitive. Because the trade deficit and foreign investment in the US are linked, waging war on the former is waging war on the latter. The consequence of that war is to reduce the wages of US workers and the incomes of US households.

Because President Trump frequently cited the (supposed) job-destroying effects of the trade deficit, the third reason that eliminating the trade deficit is a wrongheaded goal is that wiping out the trade deficit would not increase employment in the United States.

In addition, eliminating the trade deficit would be a partial retreat from economic engagement with other nations. But the post–World War II liberal international order—of which free trade is a major component—has been a bedrock of peace and prosperity on both sides of the Atlantic for seven decades.

The fifth reason relates to the role the US plays in providing liquidity to the global economy. This liquidity provision makes the trade deficit central to global economic stability. Demand for US financial assets is driven in part by the dollar’s role as the global reserve currency and as the currency in which many global transactions occur. This reduces the cost of foreign borrowing, allowing the US to consume and invest more than it produces at relatively low cost.

Finally, an assault on the trade deficit is an assault on economic liberty.

Free exchange is good. As a general matter, two parties should be left to their own judgment as to whether a voluntary transaction makes each better off, free from the interference of government. I run a substantial trade deficit with my grocery store, which makes both my family and the store better off. Similarly, free trade between individuals and businesses in different nations makes those parties better off.

Economic liberty is not an absolute good, and of course there are times when it should be curtailed. But in the absence of strong reasons for curtailing it, in a free society it should be the default position of economic policy. Indeed, a free society has little choice but to accept free trade. The economic police state required to eliminate the trade deficit would be so intrusive as to substantially reduce not just economic liberty but political liberty as well.

Moreover, Trump’s tariffs will not close the trade deficit. They will decrease, not increase, manufacturing employment. They will reduce the competitiveness of manufacturing companies.

This assault on the Constitution is in exchange for economic damage to manufacturing — and, more broadly, to workers, households, and businesses. The president prides himself on deal-making. This is a raw deal for the United States.