Back in the days before everyone had a computer, news stories would have to be retyped at least once before they could appear in print—a reporter would write the story on a typewriter or by hand, and it would make its way to a typesetter, who retyped it either into lines of hot metal or, in later years, into the electronic typesetting machine. If the story had been dictated to someone, that added another layer. Each time something was retyped, the potential increased for a letter or word to be added or dropped.

So editors and proofreaders (if you can remember what those are) learned to peruse every “public” to be sure that the “l” was still there, and some papers are rumored to have banned the word “shift” lest an “f” be dropped. And those experienced in dictation learned to repeat keywords, as in “he was not (RPT not) found in bed with the starlet.”

That is probably the derivation of reporting that someone accused of a crime has pleaded or been found “innocent.” It’s a way of assuring that someone who intends to write “not guilty” does not forget the “not,” or that “not” isn’t accidentally changed to “now.”

There are a couple of problems with that approach, however. The first is that, with copy being typed only once most of the time—the same file is passed from the writer through production—there is less chance that something will be dropped or mistyped. (Though if there is no editing process, the danger still exists.)

The more important problem, though, is that, as The New York Times Manual of Style and Usage explains: “In the American system, a defendant is presumed innocent and therefore never needs to prove innocence; it is guilt that must be proven, by the state. So a defendant’s plea (or a successful one’s verdict) is not guilty rather than innocent.”

In addition, many people who are found “not guilty” are not at all “innocent,” but have been found “not guilty” for other reasons, such as technicalities or lack of evidence.

While this may seem like splitting hairs to some—even some lawyers have fallen into the “innocence” trap—the legal plea and judgment remain, properly, “not guilty.” The Associated Press stylebook says: “In court cases, plea situations and trials, not guilty is preferable to innocent, because it is more precise legally. (However, special care must be taken to prevent omission of the word not.) When possible, say a defendant was acquitted of criminal charges.”

Bryan A. Garner, the usage expert, is also the editor-in-chief of Black’s Law Dictionary, and in both roles he pleads for the distinction to remain. “Strictly speaking, not guilty and innocent aren’t quite synonymous,” he writes in Garner’s Modern American Usage. But he acknowledges with his Language Change Index that the jury may have reached a verdict: “plead innocent” for “plead not guilty” is already at a four out of five on the index, meaning its usage is “virtually universal but is opposed on cogent grounds by a few linguistic stalwarts.”

If you’re going to be a stalwart about something, let it be something legal.

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Merrill Perlman managed copy desks across the newsroom at The New York Times, where she worked for 25 years. Follow her on Twitter at @meperl.