For over 40 years, a memorandum of understanding has stood between the Justice Department and the Federal Election Commission, and it has been duly entered into The Federal Register. It’s a guide for how Justice and the F.E.C. should interact in administering federal election law. The document recognizes that some election law violations, for whatever reason, “may not be proper subjects for prosecution as crimes” under key criminal provisions of the federal election law statutes. The document then explains how the two agencies should interact when one or the other learns of potential violations.

Here’s the key part for our purpose: When information comes to the attention of the Justice Department indicating a “probable violation” of the Federal Election Campaign Act, the document says, “the department will apprise the commission of such information at the earliest opportunity.”

Note the standard for when the Justice Department must notify the F.E.C.: when there’s a “probable violation,” a low bar compared with the standard for actually bringing a criminal prosecution that must be proven beyond a reasonable doubt.

So again, as far as anyone knows, the Justice Department never provided that notification. And there’s more. The memo further explains that when the Justice Department determines that a probable violation “does not amount to a significant and substantial knowing and willful violation” — presumably what happened when the department decided not to continue investigating the matter described in the whistle-blower complaint — then “the department will refer the matter to the commission as promptly as possible.”

This, too, the Justice Department appears not to have done.

Why does it matter? Because the F.E.C. has a host of tools available to it to enforce federal election law that are distinct from the prosecutorial tool that the Justice Department declined to exercise here. The memo makes this, too, very clear.

It says that the Justice Department’s referral of such matters to the F.E.C. will facilitate the latter’s “consideration of the wide range of appropriate remedies available to the commission.” Those include, for example, the imposition of civil penalties for certain election-law violations — which would have been made public.

And establishing a civil violation doesn’t require that violation to have required a standard of knowing and willful. It also doesn’t require proof beyond a reasonable doubt, only the much lower standard of a preponderance of the evidence. What’s more, there’s no monetary threshold for a civil violation, meaning that the Justice Department’s apparent inability to quantify the “thing of value” the president was soliciting is irrelevant to the Justice Department’s duty to notify the commission and not a bar to that agency’s potential imposition of a civil penalty.