Arthur Bloch’s Murphy’s Law Book Three: Wrong Reasons Why Things Go More! (1982) included:
   
“Kennedy’s Comment on Committees
A committee is twelve people doing the work of one.”
 
“A committee is twelve men/people doing the work of one” has been credited to John F. Kennedy (1917-1963), but pre-1982 citations of the saying have not been located.
 
   
OCLC WorldCat record
Murphy’s law book three : wrong reasons why things go more!
Author: Arthur Bloch
Publisher: Los Angeles, Calif. : Price/Stern/Sloan, 1982.
Edition/Format:   Print book : English
 
12 December 1982, Los Angeles (CA) Times, “Book Notes” by Dick Lochte, sec. R, pg. 10, col. 2:
FINALLY—“Murphy’s Law Book Three: Wrong Reasons Why Things Go More!”(Price/Stern/Sloan: $2.95) by Arthur Bloch continues to gather new bits of philosophy for our times. I.e. Kennedy’s Comment on Committees: “A committee is 12 men doing the work of one.” ...
 
6 February 1983, Arkansas Gazette (Little Rock, AR), “Book Notes” by Bill Lewis, pg. 3C, col. 4:
Bureaucracy: “A committee is 12 doing the work of one.”
(From the third Murphy’s Law book.—ed.)
   
30 October 1984, Philadelphia (PA) Inquirer, “About agents, and finer things” by Bill Lyon, pg. 1-E, col. 1:
A committee is 12 people doing the work of one.
 
Google Books
1001 More Humorous Illustrations for Public Speaking
By Michael Hodgin
Grand Rapids, MI: Zondervan
1998
Pg. 159:
Kennedy’s Committees
A committee is twelve men doing the work of one.
 
Google Books
Murphy’s Law
By Arthur Bloch
New York, NY: A Perigee Book
2003
Pg. 55:
Kennedy’s Comment on Committees
A committee is twelve people doing the work of one.
 
Google Books
5,000 Great One Liners
Compiled by Grant Tucker
London: Biteback Publishing
2012
Pg. ?:
A committee is twelve men doing the work of one.
 
Twitter
Tanay
‏@Sarcasm_Tanay
@ccchucklefest A committee is twelve men doing the work of one #KeepItLiteWithChuckle
5:37 AM - 5 Oct 2016