What is the origin of the word “copper” for referring to a police officer? [duplicate]

Question

Possible Duplicate:
What are some slang words for “police” in countries besides the US?

What is the origin of the word copper for referring to a police officer? There is no shortage of explanations available on the Web, and as near as I can tell they fall into three categories:

1. It is a variation of the Latin capere, meaning, to grab or apprehend — a meaning preserved in expressions like “cop a feel” — that came into use in Britain in the 1700s.
2. Early English police forces had very large copper helmets (or, in some versions, buttons).
3. The badges worn by early New York police officers were made of copper.

In addition, some sources have the word arising from “the color of the early police or sheriff cars in the western states”, and even from an acronym for “Constable On Patrol”.

What I can’t find is an authoritative reference on the matter. The OED entry seems to support (1) as an application of the word, at least for cop, but is ambiguous about its origin and says only that “other conjectures have been offered” for copper.

Is there a generally agreed to origin for the use of copper for referring to a police officer?

Answer 1

There probably isn't a definitive reference. The Straight Dope begins its discussion of the origin of copper with this declaration:

Etymology is rarely an exact science. Words or phrases spring up, become popular, and eventually may find their way into print. The process takes time, and it's usually difficult or impossible to track backwards to discover where a particular word or phrase arose.

The article goes on to discount the speculations raised in your points #2 and #3, and flat-out says:

The notion that cop is an acronym for "Constable On Patrol" is nonsense. Similarly, the word did not arise because police uniforms in New York (or London or wherever) had copper buttons, copper badges, or anything of the sort.

It does, however, raise the alternative theory that "to cop comes from the Dutch kapen, meaning to take or to steal."

Answer 2

It’s probably because a copper is one who cops wrong-doers. Cop in the sense of ‘capture’ or ‘catch’ is first recorded in 1704. It may be derived from the now obsolete verb cap, ‘to arrest’, from a related Old French word.

Answer 3

I was told that the original policeman were paid a penny or a copper a day as wages and hence earned the nickname of 'copper'.