... Of course there are "tapes" of Trump White House conversations — as anyone who works in a big corporation has reason to know.

As the Chicago Tribune recently pointed out, since 2011, the White House, like any state-of-the-art office, uses a Voice over Internet Protocol (VoIP) phone system, "an Internet technology that sends voice messages as packets of digitized data. The technology allows for retrieval of a text record of presidential conversations."

Trump may or may not have "taped" the Comey dinner or other non-telephonic conversations relevant to the inquiry. And yet, imagine how many telephone conversations there must have been — whether with Comey or with White House aides or outside advisers — relevant not just to the Comey firing, but to Mueller's broader brief to investigate connections between the White House and Russia.

Muller also enjoys another advantage in getting to the bottom of presidential malfeasance that Watergate-era investigators did not. After Nixon resigned the White House in disgrace in August of 1974, fears that he would destroy incriminating records in advance of his and his advisers' criminal trials led to the passage in 1978 of the Presidential Records Act.

It requires Presidents, vice presidents and their staffs to "take all such steps as may be necessary to assure that the activities, deliberations, decisions, and policies that reflect the performance of the President's constitutional, statutory, or other official or ceremonial duties are adequately documented…and maintained as Presidential records." They are then sealed for a specified interval of years — unless they are subpoenaed.

In 2014, President Obama signed legislation modernizing the PRA to specifically include electronic records. The digital clarification was necessary after it was revealed the George W. Bush White House "lost" some 22 million emails sent via a private service set up by the Republican National Committee — and recently became an issue in February of 2017 when Trump aides were reported to have been using communications apps that erase messages as soon as they're read. The White House then explicitly banned the practice. ...