Listening to a news report last week, I was informed that “four persons are being sought for the murder”. It occurred to me that I, one of our nation’s smartest people, had no idea why someone would choose people or persons in their writing. I think I understand “peoples”, as it relates to people as a population of a certain type. The world is full of various peoples. But what is the rule for people vs persons?
In the strictest of pedantic usage, a people is the totality of a nationality or ethnic group, taken as a unit with shared values. E.g., “We the people of the United States” means “all of us who are U.S. nationals, as a unified entity acting together,” not “us sturdy individualists separately”; one may speak of “the Belgian people” or alternatively “the Flemish people” and “the Walloon people” who togetherr comprise the overwheming majority of Belgians.
However, the pedants have long since lost the fight, and “people” in common usage outside an overtly demographic context means “more than one person.” E.g., “About 20 people gathered to hear the outdoor band concert despite the freezing rain.”
“Persons,” the technically correct plural, has gained a slightly disreputable odor of bureaucratese or legalese. In the example given, I would lay strong odds that it is a fast rewrite of a police press briefing, written or oral.
Those pedants were never winning this fight. “People” has essentially always been used in such contexts (the OED gives a steady stream of citations for “people” as a plural count noun in this fashion going back to 1330), and no one ever started to complain before the turn of the century (from 19th to 20th). Cite.
In The Careful Writer, Theodore Bernstein, who normally took narrow views of usage, said back in 1965:
Just to clarify, that’s one people as in “one people went to the store”, not “after 9/11 we were all one people,” a different usage.
Well, I hadn’t known they were 570 years out of date when they started, but I’m glad to ee my basic point sustained. 
Oh, and let us not forget the SDMB patron saint of unattributed anecdotal datapoints, dating back to AOL days: Manny Peoples.
(As in “Manny Peoples have told me that a jackrabbit is not really a rabbit…”)
But do we all agree on <b>Poly’s</b> definition of Persons? That was my real question. I, too, thought it was simply a function of ‘legal speak’, but why would it be?
Because lawyers, doctors and related professions love using obscure language that nobody else would. Makes them feel important and their customers awed at the wisdom of the educated.
(Pst, the code here uses square brackets - I know, why does every place use a different kind…)
I don’t agree. It’s a normal standard usage.