“Old soldiers never die—they just fade away” is an old saying that was popularized by General Douglas MacArthur (1880-1964) in his farewell address to Congress on April 19, 1951. Many parodies of the saying have been made. “Old lawyers never die. They could argue anybody out of anything,” was cited in print in July 1951.
 
“Old lawyers never die—they just lose their appeal” has been cited in print since at least March 1955; in August 1955, the line was credited to producer Peter Arnell.
 
 
4 July 1951, Cedar Rapids (IA) Gazette, “Foto Facts” by John Reynolds, pg. 5, col. 1:
Since General of the Army Douglas MacArthur made his dramatic reference to “Old soldiers never die - they just fade away” there has been a flood of parodies.
(...)
12. Old lawyers never die. They could argue anybody out of anything.
 
23 March 1955, San Antonio (TX) Light, “Bexar Facts” by Ed Castillo, pg. 25, col. 1:
Budding attorneys: Young Douglas Jones, son of Judge M. D. “Buck” Jones, asked Jay Westbrook, son of Atty. Joel Westbrook, if he knew “old lawyers never die, they just lose their appeal.”
 
30 April 1955, Dallas (TX) Morning News, “Down to Earth” by Dr. John F. Anderson, Jr., pt. 1, pg. 1, col. 1:
“OLD BANKERS never die; they just lose interest! Old lawyers never die; they just lose their appeal!”
 
31 August 1955, Aberdeen (SD) American-News, “It Happened Last Night” by Earl Wilson, pg. 4, col. 5:
“OLD LAWYERS never die,” reports Peter Arnell, “they just lose their appeals(s).”
 
9 December 1956, Chicago (IL) Tribune, “Radio-TV Gag Bag” by Larry Wolters, pg. K28:
Peter Arnell told his lawyer: “Old lawyers never die. They just lose their appeal.”
 
Google Books
Courtroom Kicktales
By John G. May
Charlottesville, VA: Michie Co.
1964
Pg. 37:
Old Lawyers
Old lawyers never die. They just lose their appeal.
As told by BILL WHITLOCK
 
Google News Archive
11 September 1964, The Herald (Calgary, Alberta), “Johnny Hopkins reports,” pg. 23, col. 1:
Old lawyers never die, they just lose their appeal.
 
Google Books
The New Lawyer’s Wit and Wisdom:
Quotations on the Legal Profession, in Brief
By Bruce M. Nash, Allan Zullo and Kathryn Zullo
Philadelphia, PA: Running Press
2001
Pg. 53:
Old lawyers never die, they just lose their appeal.
ANONYMOUS