The ousting of a democratically elected president, the defence argued, would be a unique and momentous decision out of all proportion to the offences alleged and the achievements of his presidency. The last president to be subject to Senate trial, Andrew Johnson in 1868, was acquitted by a single vote.
To bolster their case, in style as well as substance, the defence team had co-opted Dale Bumpers, the newly retired Democrat senator from Mr Clinton's home state of Arkansas, to deliver the closing statement. Mr Bumpers, whose departure from the Senate last year was lamented in Washington and in his home state equally as the end of an era, lent to the White House defence the flights of soaring rhetoric and lofty principle that its arguments had mostly lacked.
Mr Bumpers was valuable not only as a practised advocate in the style to which the Senate aspires, but as an Arkansan, familiar with the President's background and the political mores of his home state. According to Arkansas natives, the shenanigans in and around the capital, Little Rock, at least in the past, make whatever Bill Clinton was up to in the White House look like adolescent naivete.
Mr Bumpers' closing oration followed two-and-a-half days in which defence lawyers had concentrated on the small print of the allegations against the President to cast doubt, if not completely discredit, the charges against him. On the opening day, Charles Ruff, the White House chief counsel, had challenged the evidence that Mr Clinton had instigated the concealment of presents that he had given to Monica Lewinsky.
The following day, Gregory Craig had cast doubt on the specific perjury charges against him, insisting that he never lied under oath, and Cheryl Mills - young, black and a White House deputy counsel - attacked the obstruction of justice charges and pleaded Mr Clinton's civil rights record in mitigation of his non-offences. Ms Mills, whose impassioned performance made her an overnight star in Washington, moved some senators close to tears with her defence of the "civil rights" President.
Yesterday, though, belonged to Dale Bumpers, whose contribution brought to a close six days of presentations - three by the House of Representatives' "prosecutors" and three by the White House - that have been increasingly lauded as attaining the height of judicial professionalism. They have also left the case exceptionally finely balanced, as prepared statements give way to two days of written questions from the senators.
Outside the Senate chamber - but perhaps even starting to seep inside - seemed to be a growing view that the trial might, after all, be concluded without calling "live" witnesses. Some believed that the combination of doubt cast on the evidence and Mr Clinton's triumphant State of the Union address combined to make the case against him unanswerable. Others felt that witnesses might be questioned by lawyers but that their answers would be sufficient, without the need for them to appear in person.
With even one of the President's fiercest critics, the right-wing evangelist, Pat Robertson, saying publicly that in his view it was "all over" and that Mr Clinton's State of the Union address had clinched it, the prospect of conviction looked even slimmer than before.
On Monday, the 100 senators are scheduled to vote on whether to dismiss the case or continue to the hearing of witnesses. The trial looks likely to continue.