A look at the main points Democrats are making as they argue for Trump's removal from office, and Trump's response as the defense team pushes for his speedy acquittal. The GOP arguments have already raised charges of distortion.
ON ABUSE OF POWER
Democrats say Trump abused the power of his office by urging Ukrainian President Volodymyr Zelenskiy in a July 25 phone call to announce an investigation of political rival Joe Biden and the Democrats. At the time, Trump was withholding hundreds of millions of dollar in military aid to the country.
The sought-after investigation into Biden, as well as into a baseless theory that Ukraine had interfered in the 2016 presidential election, was a solicitation to interfere in U.S. politics — and served the political interests of the president rather than the national security interests of America, Democrats say,
Trump's lawyers, meanwhile, contend there's no evidence beyond hearsay that the president conditioned the release of aid on Ukraine agreeing to an investigation.
The money was released without any investigations being undertaken — and, they say, Zelenskiy didn't even know it had been suspended until shortly before it was released, even though U.S. officials testified to House investigators that Ukraine had inquired about the delay.
The legal team says that Trump had legitimate concerns about corruption in Ukraine and that it was appropriate for him to bring up Biden on the call since his son Hunter sat on the board of a gas company, Burisma, that was suspected of corruption.
Trump has sought, without evidence, to implicate the Bidens in the kind of corruption that has long plagued Ukraine. Hunter Biden served on the board of Burisma at the same time his father was leading the Obama administration's diplomatic dealings with Kyiv. Though the timing raised concerns among anti-corruption advocates, there has been no evidence of wrongdoing by either the former vice president or his son.
In any event, Trump's lawyers said pauses on foreign aid are neither unusual nor inappropriate, and it's a decision that rests squarely with the commander of chief. Presidents have the right to exert their authority without their political opponents second-guessing their motive or intent, they argue.
ON OBSTRUCTION OF JUSTICE
The Trump administration obstructed Congress every step of the way during the impeachment investigation, directing witnesses not to testify or turn over documents, according to House Democrats who pointedly note that it is the House — and not the White House — that gets to determine the scope of a such an inquiry.
They say that witnesses who did choose to come forward, either publicly or privately, endured public statements from the president that appeared aimed at discouraging them from cooperating. And multiple government agencies, including the State and Energy departments, followed the lead of the White House and refused to turn over documents.
The Trump legal team says there's nothing novel about the administration's defiance.
The lawyers said close and senior advisers to the president have long been understood to be immune from congressional testimony. On Monday, they pointed to opinions from the Justice Department's Office of Legal Opinion that supported that stance.
The lawyers noted that lawmakers began issuing subpoenas to witnesses even before the full House had formally voted on rules for the impeachment inquiry, something the Justice Department says makes those subpoenas legally unenforceable. Democrats say the House has the "sole power of impeachment," so the process can't be second-guessed by the administration.
When White House officials blocked Trump's advisers from testifying or turning over documents, defense lawyers say, they were protecting the prerogative of the presidency — and not obstructing an investigation.
ON WHAT CONSTITUTES AN IMPEACHABLE OFFENSE
Democrats say Trump's conduct is precisely what the country's Founding Fathers had in mind when they created the mechanism to impeach and remove a president from power. Not only that, they described it in a filing as the framers' "worst nightmare."
The Constitution sets a standard of "Treason, Bribery, or other high Crimes and Misdemeanors" for impeachment, and according to Democrats, it's a flexible enough threshold to "reach the full range of potential Presidential misconduct."
Whether the allegations need not amount to crimes is a very significant point of contention. Trump's lawyers state contend that an impeachable "offense requires especially egregious conduct that threatens the constitutional order and, specifically, that it requires a violation of established law."
Nothing the president is accused of, they say, comes close to meeting that standard. And removing Trump from office under these facts would dilute the standards of impeachment, permanently weaken the power of the presidency and allow a "hostile House to attack almost any presidential action by challenging a President's subjective motives."
One member of the president's legal team, Alan Dershowitz, said in Sunday talk shows that an impeachable offense must amount to "criminal-like conduct." Some legal scholars have strongly disputed that stance, and Rep. Adam Schiff, the Democratic chairman of the House intelligence committee, called it an "absurdist position."
Ultimately, it's up to the Senate to decide. A two-thirds vote on either charge is required to convict the president and remove him from office.