[Ads-l] "cop" < "copper": Etymology, etymythology, or Scotch verdict?

[Laurence Horn]

From a review in the NYTBR of a new history of the New York Police Department:

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https://www.nytimes.com/2017/06/28/books/review/law-and-disorder-nypd-bruce-chadwick.html

Chadwick can be sloppy in his word choices. Early on he uses the descriptions “cops” and constables interchangeably, but then explains that the term “cop” was born later, when police officers got copper badges. 
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This suggests that author Chadwick and/or reviewer Jamieson assume that “cop” in fact derives from NYPD (or other) constables’ wearing copper badges.

Now we know that the derivation of “cop” from “Constable On Patrol” is a classic faux-acronymic etymythology, right up there with POSH, NEWS, GOLF, WOG, and FUCK. But I always thought “cop” < “copper” was also generally dismissed, and that the standard wisdom is that it’s a conversion/zero-derivation from the verb “to cop” (‘take, capture, nab’).  At first glance it seems as though the OED seems to allow for both possibilities, along with various cites going back to the 1840s and 1850s:

Cop, n. 5 
Etymology: Compare cop v.3 and copper n.4

However, on closer examination, *this* “copper” is not the metal used in badges (= copper n.1), but rather an agentive noun derived from the above verb:

Copper n.4
Etymology: apparently < cop v.3; but other conjectures have been offered.

So that would mean a derivation along the lines of 

cop, v. ‘to seize’ > copper ‘one who cops’ > cop (by clipping)

—which seems to suggest that the idea that “cop" has anything to do with the copper in badges is indeed an etymythological reconstruction—or is it?  (The “other conjectures have offered” does leave the door open, to something.) 

AHD5 supports the same two-stage derivation, verb to agentive noun to truncated form:

cop, v. >  copper ‘one who cops’ > cop, n.

Can the derivation from copper badges be definitively rejected?  Is current slang “copper” a remnant from the earlier noun—

1846   Sessions Papers 16 May 39   I have heard the police called coppers before.

(Seems like current “copper”, at least in the U.K., is used in the sense of ‘informant’ rather than ‘police officer’, judging from the OED cites.)

Does anyone else know more about the genealogy of “cop"? 

LH
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