Liberal law professor Jonathan Turley, who testified as a witness during the impeachment inquiry of President Donald Trump, has some tough words for Democrats.

According to the constitutional law expert, Democratic House leaders' impeachment case against the nation's 45th president "collapses under [the] weight of time." In an article in The Hill, Turley argues that although Democrats could have mounted a credible prosecution against Trump, their rush to impeach him before Christmas undermined one of the two articles of impeachment they approved.

'Obstruction of Congress' is not holding up

Specifically, Turley wrote that the "obstruction of Congress" charge no longer holds any water. Both in his testimony before the House and in his op-ed, Turley says that Trump did not "obstruct" justice or Congress by seeking judicial reviews of the House's subpoena requests.

I was particularly concerned about moving forward by Christmas on the second article of alleged obstruction of Congress. The House elected to push through impeachment with an abbreviated period of roughly three months and declared any delay by Trump, even to seek judicial reviews, to be a high crime and misdemeanor. The administration is currently in court challenging demands for witnesses and documents. Just a couple weeks ago, the Supreme Court accepted one such case for review then stayed the lower court decisions ordering the production of the tax and finance records of Trump. The House impeached Trump before that court or other federal courts could rule on the merits of claims of presidential privileges and immunities. Both Bill Clinton and Richard Nixon had been able to take such challenges to the Supreme Court before they faced impeachment.

Obama and Biden could have been impeached under the Democrats' standard

In fact, Turley noted how former President Barack Obama and even Joe Biden, who says he would ignore a Senate subpoena request, could be impeached under the House Democrats' "obstruction of Congress" standard.

The respected constitutional law professor also singled out Reps. Eric Swalwell (D-Calif.) and House Intelligence Chair Adam Schiff (D-Calif.) for undermining the credibility of the Democrats' case.

It is unclear if [Rep. Eric Swalwell's] concept of due process would be extended to President Obama, who refused both critical witnesses and documents to Congress on the basis of claims that were eventually dismissed by federal courts as untenable. Likewise, former Vice President Joe Biden has made headlines by declaring that, if subpoenaed, he would defy the Senate. But someone must have explained to Biden that the man he seeks to replace was just impeached for defying the House, even without a subpoena, because he clarified his earlier remarks by stating the opposite in a later interview.

Turley concluded that the country "will likely witness the collapse of a Senate trial" because of House Democrats' zealotry and eagerness to impeach Trump before the holiday season.