JOSH BLACKMAN & SETH BARRETT TILLMAN: The ‘Resistance’ vs. George Washington: If a president can’t take emoluments, the founders were crooks.

The Trump administration has been under siege from the left’s self-professed “legal resistance.” Perhaps the highest-profile example involves President Trump himself. Several lawsuits allege that his business interests run afoul of the Constitution’s Foreign Emoluments Clause.

The Justice Department has done a good job defending the president’s actions on most issues—but not on this one. The department still has refused to make its strongest argument: that the Foreign Emoluments Clause does not apply to the president. The Trump administration needs to throw out a 2009 opinion from the department’s Office of Legal Counsel that concluded, without any analysis, that the Foreign Emoluments Clause “surely” applied to President Obama. Instead the department should defend the president’s unitary role in the separation of powers—a position the Constitution supports. . . .

History backs up this reading. Treasury Secretary Alexander Hamilton set the precedent in 1793: When the Senate requested a financial statement listing the “emoluments” of “every person holding any civil office or employment under the United States,” Hamilton’s comprehensive report excluded all elected offices—the president, vice president and members of Congress—but included appointed positions in all three governmental branches.

George Washington accepted, as a diplomatic gift from France, a framed full-length portrait of King Louis XVI. Thomas Jefferson accepted a bust of Czar Alexander I from Russia. Neither president sought Congress’s consent to keep the gifts.

But for some reason the Trump administration continues to stand by the 2009 opinion, drawn up when Mr. Obama was being awarded the Nobel Peace Prize, which came with a $1.4 million award. The Office of Legal Counsel concluded Mr. Obama could accept the money, but the opinion simply assumed the Foreign Emoluments Clause applied to the presidency. It was taken as a given with no citations either to judicial rulings or to the practices established by Washington and other founders.

The Obama Justice Department was a disaster, and much of it is still employed under Trump.