Mon, 14 May 2007
Bryan and his posse
A pitched battle was fought..at Rockhill, Missouri, between the Sheriff's posse and the miners on strike.
From the context and orthography, I guessed that it was from Spanish. But no, it's not. It's Latin! "Posse" is the Latin verb "to be able", akin to English "possible" and ultimately to "potent" and related words. I'd guessed something like this, supposing English "posse" was akin to some Spanish derivative of the Latin. But it isn't; it's direct from Latin: "posse" in English is short for posse comitatus, "force of the county".
The Big Dictionary has citations for "posse comitatus" back to 1576:
Mr. Sheryve meaneth in person to repayre thither & with force to bryng hym from Aylesham, Whomsoever he fyndeth to denye the samet & suerly will with Posse Comitatus fetch hym from this new erected pryson to morrow.
"Sheryve" is "Sheriff". (If you have trouble understanding this, try reading it aloud. English spelling changed more than its pronunciation since 1576.)
I had heard the phrase before in connection with the Posse Comitatus Act of U.S. law. This law, passed in 1878, is intended to prohibit the use of the U.S. armed forces as Posse Comitatus—that is, as civilian law enforcement. Here the use is obviously Latin, and I hadn't connected it before with the sheriff's posse. But they are one and the same.