Democrats continue to argue that the Senate impeachment trial of President Donald Trump requires further witnesses and documents. What kind of trial does not include witnesses and documents? they ask.

But the Senate has just heard witnesses and seen documents for nearly 30 hours over three days — including during a marathon opening session that was supposed to debate procedural motions, not to explore the substance of the charges against the president.

House impeachment managers have used clips from witness testimony in the public hearings that Rep. Adam Schiff (D-CA) conducted in the House Intelligence Committee. Senators have been forced to sit silently as Schiff and his team have played endless video “evidence” — some of it deceptively edited to distort the witnesses’ testimony.

Most of the testimony would be excluded from an ordinary trial as hearsay evidence. But Senators have seen and heard it.

Not one of the witnesses was cross-examined in the House by the president’s lawyers, because Democrats broke with precedent and did not allow White House counsel to participate in the fact-finding phase of the investigation.

Nor did Schiff or House Judiciary Committee Chairman Rep. Jerry Nadler (D-NY) let Republicans call any new witnesses.

Now they want the Senate to allow them to do what Democrats refused to allow Republicans to do in the House.

Moreover, for all the talk of bringing in new witnesses like acting White House Chief of Staff Mick Mulvaney, Senators have already heard from Mulvaney, because House impeachment managers have played video from the press conference in which he discussed Ukraine.

And as for documents, Democrats have repeatedly shown or described documents to the Senate that were never discussed or debated during the House Intelligence Committee inquiry.

The most striking of these documents are the phone records that Schiff obtained on Ranking Member Rep. Devin Nunes (R-CA), journalist John Solomon, presidential lawyer Rudy Giuliani, and former Giuliani associate Lev Parnas. Schiff only revealed these phone records in the House Intelligence Committee impeachment report.

House impeachment managers have made all kinds of accusations based on these records, though their accuracy is in doubt.

Worse, the records were likely obtained unlawfully, and arguably violate the president’s constitutional rights. No ordinary criminal court would ever admit them as evidence. Yet Senators have heard about them for three days.

So for all the talk of “witnesses” and “documents,” Democrats have already had plenty. Republicans and the White House have had none.

The defense does not need to call witnesses — not when prosecutors fail to prove their case.

But if Democrats get their wish — and they might — to call new witnesses, such as former National Security Advisor John Bolton, then the White House will call witnesses of its own.

It is not clear what value Bolton would provide to a case that House Democrats already say is “overwhelming.”

And after an inevitable court battle over executive privilege, one that would drag the trial out for weeks, Bolton might not be able to say much to the Senate anyway.

But the Senate would be able to compel the testimony of former vice president Joe Biden about what he has already admitted “looked bad” — namely, that the son earned a mint from Burisma while the father ran U.S. Ukraine policy.

And the White House would invoke the president’s Sixth Amendment right to cross-examine his accuser — the elusive “whistleblower,” whom Democrats hid.

Arguably, the public has a right to know who started this, and why.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He earned an A.B. in Social Studies and Environmental Science and Public Policy from Harvard College, and a J.D. from Harvard Law School. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.