The declaration comes after months of speculation and two years of failed negotiations over fortifying the southern border.
Even before Special Counsel Robert Mueller finishes his investigations of Donald Trump, the president's effort to usurp Congress' power of the purse under Article I of the Constitution itself warrants his impeachment.
Perhaps unwittingly, he admitted the fallacy of his allegation that building his vanity wall on the southern border constituted a national emergency, by acknowledging, "I didn't need to do this," and, "I just want to do it faster."
Mr. Mueller meanwhile pursues grounds to charge Mr. Trump campaign associates -- and perhaps the president himself -- with conspiracy with Russia in tampering with the 2016 election, and with obstruction of justice. In 2017, Mr. Trump infamously asked then-FBI director James Comey to go easy on National Security Adviser Michael Flynn, who was being investigated for lying to FBI agents about a meeting with the Russian ambassador. Mr. Flynn subsequently pleaded guilty to the charge in a deal with the government.
But Trump already deserves impeachment for failing to "faithfully execute the Office of President" and to "preserve, protect and defend the Constitution," as stipulated in its Article II on presidential power. He has acknowledged that the judicial system is poised to challenge him in lower jurisdictions on up to the Supreme Court, where he predicts eventual victory.
The federal judiciary, however, has been notably willing to take him on over the reach of that presidential power in the context of the rock-bottom American separation of powers. Even the two Trump-nominated freshman justices will have to think hard about overlooking their benefactor's naked power grab.
Our judicial process is quite often a slow and deliberative one, as it should be, and considerable time may pass before any decision of major significance is reached. For that reason alone, the issue should be undertaken in the lower courts as soon as possible, as Mueller continues at his laborious pace on his fact-gathering about Trump's other potentially impeachable offenses.
The rollout of Mr. Trump's national emergency declaration was typical of his erratic, amateurish approach to major policy announcements. It was short on details about implementation and long on show business. Survivors of victims of border violence, dubbed "angels," were conveniently present and introduced to testify to the president's anti-criminal initiatives regarding immigrants.
A disjointed news conference followed with questions at first ranging far from the emergency issue, about which Mr. Trump randomly winged it in his remarks. He even acknowledged that he would probably get "bad rulings" at the lower court level.
"We will then be sued, and they will sue us in the Ninth Circuit [in New York] even though it shouldn't be there," he said, "and we will possibly get a bad ruling, and then we'll get another bad ruling, and then we'll wind up in the Supreme Court, and hopefully we'll get a fair shake and we'll win in the Supreme Court."
The latter remark seemed to forecast payback from his two appointments of Justices Neil Gorsuch and Brett Kavanaugh, whose votes understandably would undergo close scrutiny. So would that of Chief Justice John Roberts, a conservative choice of President George W. Bush, who has occasionally strayed from the Republican flock in ideological rulings.
The news conference soon disintegrated into the customary Trump self-praise, including a previously undisclosed letter from Japanese Prime Minister Abe Shinzo that Mr. Trump said he had received saying he should receive the Nobel Peace Prize. Actually, South Korean President Moon Jae-in is alleged to have made the comment.
Our president, who recently said we probably would be at war with North Korea had he not been elected, took this occasion to deliver a gratuitous slap at his predecessor in the Oval Office, observing of the prize: "I'll probably never get it, but that's OK. They gave it to Obama. He didn't even know what he got it for. He was there for about 15 seconds and he got the Nobel Prize."
So it goes with this man demonstrably unfit for the bigger prize he did win two years ago. He has gone too far this time by stealing the power of the purse from the legitimate appropriators of the nation's treasury.
Another question of equal import now is which of the Republican leaders in Congress have had enough of Mr. Trump's destructive actions to save the Grand Old Party from its own demise. In approaching congressional votes, they will have the opportunity to reject the president's overreach in his national emergency declaration.
Jules Witcover is a syndicated columnist and former long-time writer for The Baltimore Sun. His latest book is "The American Vice Presidency: From Irrelevance to Power" (Smithsonian Books). His email is firstname.lastname@example.org.