At the meeting, O'Neil presented a letter in which he said the Justice Department had "advised" him that Yates' official communications on issues of interest to the House panel are "client confidences" that cannot be disclosed without written consent. O'Neil challenged that interpretation as "overbroad" in the letter.
The following day, in a letter to O'Neil, the Justice Department responded with another objection: that Yates's communications with the White House are probably covered by "presidential communications privilege," and referred him to the White House. A Justice Department spokeswoman declined to comment.
O'Neil then wrote to White House Counsel Donald McGahn, saying that he believed any privilege had been waived as a result of past White House statements and that Yates planned to testify unless he heard back from McGahn.
But that same day, the hearing, which also would have included former CIA director John Brennan and former director of national intelligence James Clapper, was cancelled by the House Intelligence Committee's chairman, Devin Nunes, and any White House decision on Yates's testimony became moot.
In his briefing yesterday, press secretary Sean Spicer said that the White House did not weigh in on whether Yates could testify. "To suggest in any way, shape or form that we stood in the way of that is 100 percent false," he said.
Nunes has said he cancelled the hearing to first hear from FBI Director James Comey in a classified setting. That session was also cancelled.
Democrats charge that Nunes has aligned himself too closely with the White House to conduct an independent probe.
"You see the unravelling of this committee happening overnight for no good reason," said Rep. Jackie Speier, a committee member. "We have a responsibility to do this investigation."