When President Obama flies to Havana Sunday to cozy up to the Castros, he’ll take off from a runway other than the Constitution. He’ll be violating the letter and the spirit of congressional statute, too. This is one of the under-appreciated features of Mr. Obama’s effort to make Communist Cuba a central part of his legacy. Even against his record on Iran, it’s hard to think of a foreign policy adventure quite like it.

On the one hand, the President is taking along corporate executives in an effort to “kick start,” as USA today puts it, a business relationship. On the other hand, trading with Cuba is embargoed by Congress. It’s not legal. Even tourism is strictly controlled by Congress, which limits such travel to visits that have an educational purpose. Yet the President announced measures this week that make a mockery of Congress.

No one has changed the law that imposes the tourism ban. But, as the New York Times gleefully explains in an editorial this week, proving that a trip has “educational purposes” will now “rest with the travelers.” And, it adds helpfully, “any seasoned traveler will tell you that conversations with bartenders, beachside or not, can be mightily educational.” How does this comport with Mr. Obama’s oath to “faithfully” execute his office?

The incredible thing is that in the 1990s, Congress passed a historic law setting the conditions under which America could begin normalizing relations with Cuba. The measure is called the Cuban Liberty and Democratic Solidarity Act. It’s also known as Libertad, or the Helms-Burton. Congress passed the act under its authority to regulate commerce with foreign nations, extending the ban on Cuba trade to foreign companies doing business with America.

The terms and conditions it lays out are explicit. It establishes that before the American embargo can be relaxed, the president must determine — and report to Congress — that a transition government is in power. To qualify Cuba’s government must have, among other things, “legalized all political activity,” “released all political prisoners,” committed to “free and fair elections for a new government” with the participation of “multiple independent political parties.”

Also required is progress toward an independent judiciary, freedom for independent labor unions, assurance of private property rights. Plus, a transition government can only be one that “does not include Fidel Castro or Raul Castro.” That is the law of the land, passed by Congress and signed not by Ronald Reagan or George W. Bush but President Bill Clinton. Yet Mr. Obama and the Left intelligentsia are plunging ahead like the Constitution and Congress mean nothing.

We comprehend that there are free market conservatives who oppose the embargo in respect of Cuba. Among them is the editorial page of the Wall Street Journal. Its Review & Outlook column is as principled an editorial column as has ever been set into type, and it has maintained the same principles for more than a century. But it’s hard to imagine it would credit abandoning the legislative process altogether.

“Even as the Obama administration has lobbied Congress to repeal the embargo, some federal officials are still, inexplicably, enforcing aspects of it,” is the way the Times sums up its point. Got it? Congress has several times considered repealing the embargo and several times concluded it does not want to repeal the embargo. Yet the Times finds it “inexplicable” that the administration is still enforcing the embargo. In respect of what other laws that Congress hasn’t repealed is enforcement “inexplicable”?