There's a phenomenon known as the "Friday night news dump," which is exploited precisely because it's often effective. It's a straightforward strategy: those who have to release information they don't want people to see will wait until late on a Friday to share the information, increasing the odds that the news will be overlooked.

A few days ago, we saw a classic of the genre, which shouldn't be discounted. The Washington Post reported over the weekend:

Hours after the Senate voted against seeking new evidence in the impeachment case against President Trump, the administration acknowledged the existence of two dozen emails that could reveal the president's thinking about withholding military aid to Ukraine. In a midnight court filing, the Justice Department explained why it shouldn't have to unredact copies of more than 100 emails written by officials at the Office of Management and Budget and the Defense Department about the hold on funds to Ukraine.

At issue are two dozen emails -- including a June 24 email sent between Pentagon officials with "POTUS follow-up" in the subject line -- the White House wants to keep under wraps. According to Heather Walsh, an OMB lawyer, these secret emails are protected by "presidential privilege."

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"Specifically, the documents in this category are emails that reflect communications by either the President, the Vice President, or the President's immediate advisors regarding Presidential ­decision-making about the scope, duration, and purpose of the hold on military assistance to Ukraine," Walsh wrote in her midnight filing.

And while there's room for a spirited debate about the merits of the administration's legal argument, let's not miss the forest for the trees: the existence of these emails is of great significance. We are, after all, talking about hidden documents that reportedly shed light not only on the nature of the president's illegal extortion scheme, but also why he launched it.

In theory, these are exactly the kind of materials senators should want to see before voting on whether to convict or acquit Trump in his impeachment trial.

A CNN report added, "The filing, released near midnight Friday, marks the first official acknowledgment from the Trump administration that emails about the President's thinking related to the aid exist, and that he was directly involved in asking about and deciding on the aid as early as June. The administration is still blocking those emails from the public and has successfully kept them from Congress."

Senate Minority Leader Chuck Schumer (D-N.Y.) released a written statement on Saturday that read, "Every single Republican Senator voted to endorse the White House cover-up of these potentially important truth-revealing emails. Make no mistake, the full truth will eventually come out and Republicans will have to answer for why they were so determined to enable the president to hide it."

House Intelligence Committee Chairman Adam Schiff (D-Calif.), who's leading the House impeachment managers' efforts in the Senate, raised a related point in his closing remarks late Friday.

"The facts will come out in all of their horror," Schiff reminded senators. "The documents the president is hiding will come out. The witnesses the president is concealing will tell their stories. And we will be asked why we didn't want to hear that information when we had the chance."

MORE: Today's Maddowblog