Double Genitive in Grammar

In English grammar, the double genitive is a phrase in which possession is indicated by the preposition of followed by the possessive form of a noun or pronoun, as in a friend of Eric's. Also called a double possessive, an oblique genitive, and a postgenitive. Some linguists argue that the double genitive is not a true genitive but rather a type of partitive construction.

In The Careful Writer (1965), Theodore Bernstein noted that "Grammarians have argued over the origin and nature, but not the validity, of the double genitive with the fervor of hot-stove league fans rehashing a Word Series play."

Examples and Observations

• The Dude: Who are you, man?
  Knox Harrington: Oh, just a friend of Maudie's.
  (The Big Lebowski, 1998)
• We heard the news from a neighbor of Alice's.
• "My bedroom, like that of my potential roommate's, is cell-like in both its size and simplicity, furnished with only a bed and a small chest of drawers that easily accommodates the little I brought with me."
  (David Sedaris, "Naked," 1997)

Bernstein's Defense of the Double Genitive

"Not infrequently someone questions a construction that reads like this: 'He is a political associate of the President's.' Since the of indicates the possessive (genitive), the someone argues, why tack on another possessive in the form of 's? Grammarians differ as to the origin and explanation of the construction, but they do not question its well-established legitimacy. . . 
"[T]he double genitive is of long standing, idiomatic, useful and here to stay."
(Theodore Bernstein, Miss Thistlebottom's Hobgoblins. Farrar, 1971)

An Idiomatic Construction

"Despite their apparent redundancy, double genitive constructions such as a friend of ours or no fault of Jo's are established English idiom. Grammarians since C18 have puzzled over the way the construction iterates the of genitive with a genitive inflection on the following pronoun or personal noun."
(Pam Peters, The Cambridge Guide to English Usage. Cambridge University Press, 2004)

A Subtle Difference

"To say you're a friend of Greg's means that Greg looks upon you as a friend. To say you're a friend of Greg means that you look upon Greg as a friend. A subtle difference. It seems that the addition of -s to . . . Greg is a way of focusing attention on [this person] as having a more active role in the relationship being expressed. Double possession has given us a way to express quite fine distinctions that we couldn't convey before. The extra marking is not overkill in this case."​
(Kate Burridge, Weeds in the Garden of Words: Further Observations on the Tangled History of the English Language. Cambridge University Press, 2005)

Purists and Language Liberals

"A good many of us do use some double genitives and do not notice that they are double. Some language liberals argue that in informal and casual contexts the double genitive is idiomatic and not overkill, but few editors of Standard English will be likely to let it stand in formal writing. It's either friends of my sister or my sister's friends; even in conversation, friends of my sister's may grate harshly on some purists' ears."
(Kenneth Wilson, The Columbia Guide to Standard American English, 1993)

"The double possessive is a matter of some controversy. Some insist that constructions like 'a friend of Bill's' are redundant and therefore should be avoided. Others see 'an old pal of mine' and extrapolate that, because you'd never say 'an old pal of me,' you also must reject 'a friend of Bill.'

"I say trust your ear over either dogma. 'A friend of Bill's' probably is better . . .."
(Bill Walsh, Yes, I Could Care Less: How to Be a Language Snob Without Being a Jerk. St. Martin's Press, 2013)