IN TODAY’S WALL STREET JOURNAL, David Rivkin, Jr. and Elizabeth Price Foley: The Case for Suing the President: Rewriting ObamaCare laws on the fly is a violation of the constitutionally mandated separation of powers.

‘So sue me” is President Obama’s message to Congress. And on Wednesday the House of Representatives took up his taunt, authorizing a lawsuit to challenge the president’s failure to faithfully execute provisions of the Affordable Care Act as passed by Congress. The House lawsuit is no “stunt,” as Mr. Obama has characterized it. The lawsuit is necessary to protect the Constitution’s separation of powers, a core means of protecting individual liberty. Without a judicial check on unbounded executive power to suspend the law, this president and all who follow him will have a powerful new weapon to destroy political accountability and democracy itself.

Article I of the Constitution vests all legislative power in Congress. Article II imposes a duty on the president to “take care that the laws be faithfully executed.” When a law is unambiguous, the president cannot rewrite it to suit his own preferences. “The power of executing the laws,” as the Supreme Court emphasized in June in Utility Air Regulatory Group v. EPA, “does not include a power to revise clear statutory terms that turn out not to work in practice.” If a law has defects, fixing them is Congress’s business.

These barriers between the branches are not formalities—they were designed to prevent the accumulation of excessive power in one branch. As the Supreme Court explained in New York v. United States (1992), the “Constitution protects us from our own best intentions: It divides power among sovereigns and among branches of government precisely so that we may resist the temptation to concentrate power in one location as an expedient solution to the crisis of the day.”

The barriers also reflect the Framers’ belief that some powers are better suited for a particular branch of government because of its institutional characteristics.

Yep. And, relatedly, the Wall Street Journal editorializes: So Sue Him: Forget impeachment. The House lawsuit is the real threat to Obama.

The House challenge involves crucial questions about the architecture of American government and the separation of powers—questions that haven’t been joined in this kind of challenge at the courts. Mr. Boehner contends that Mr. Obama’s habit of amending or suspending (not enforcing) statutes that conflict with his political goals have usurped “all legislative powers herein granted” by Article I to Congress. . . .

The Supreme Court has already responded when this President’s law-breaking has been challenged by private parties. This past term the Supreme Court rebuked the White House for its unilateral overreach in appointment powers (Noel Canning), unlawfully rewriting the Clean Air Act (Utility Air Regulatory Group) and infringing on religious freedom (Hobby Lobby). . . .

Yet Mr. Obama’s claim that he can pick and choose which laws to enforce is far more offensive to the American tradition than anything the government has done in the name of antiterrorism. The House challenge is an opportunity to vindicate the genius of the Framers to prevent the exercise of arbitrary and centralized power.

Stay tuned.