A popular lawyer joke is:
   
“What’s the difference between a good lawyer and a bad lawyer? A bad lawyer can let a case drag on for years; a good lawyer can make it last even longer.”
   
The joke has been cited in print since at least 1997.
           
 
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desperately need advice
Larry Rogers
2/28/97
(...)
Remember this little joke.  “A bad lawyer can delay a case for months…a good lawyer can do it even longer.”
 
17 May 1997, Evening Post (Wellington, New Zealand), “Last Word,” pg. 60:
Featherston St joke circuit includes this: What’s the difference between a good lawyer and a bad lawyer? A bad lawyer can let a case drag on for years; a good lawyer can make it last even longer.
     
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Deadbeat yanks
The Goblin Wizard
12/3/98
(...)
> Basically, there was doubt in congress about the entire F-111 program,
> so production of the F-111 was in danger of being stopped.  Congress
> is known to be very competent in delaying things, but then most
> politicians are lawyers, and a bad lawyer can delay things for years.
> A good lawyer can delay things even longer.
 
16 November 2000, Daily Mail (London, UK), “Why don’t sharks attack lawyers? Professional courtesy?” by Julian Champkin, pg. 13:
Q: What is the difference between a good lawyer and a bad lawyer?
A: A bad lawyer can let a case drag on for several years. A good lawyer can make it last even longer.
       
Google Books
Murphy’s Law:
The 26th Anniversary Edition
By Arthur Bloch
New York, NY: A Perigee Books
2003
Pg. 169:
Dalton’s Law
A bad lawyer can let a case drag on for several years. A good lawyer can make it last even longer.
 
Google Books
Forbes
Volume 180, Issues 1-7
2007
Pg. 134:
There’s an old joke that goes, “What’s the difference between a good lawyer and a bad one?” Answer: “A bad lawyer can let a case drag out for years. A good lawyer can make it last even longer.”
   
Google Books
The World’s Funniest Lawyer Jokes:
A Caseload of Jurisprudential Jest
By Steven D. Price
New York, NY: Skyhorse Publishing
2011
Pg. 108:
Q: What’s the difference between a bad lawyer and a good lawyer?
A: A bad lawyer can let a case drag out for several years. A good lawyer can make it last even longer.
 
Google Books
Lawyering from the Inside Out:
Learning Professional Development through Mindfulness and Emotional Intelligence
By Nathalie Martin, et al.
New York, NY: Cambridge University Press
2018
Pg. 51:
What’s the difference between a good lawyer and a bad lawyer? A bad lawyer can let a case drag out for several years. A good lawyer can make it last even longer.
 
The News-Register (McMInnville, OR)
April 6, 2018  
Jeb Bladine: Expensive lessons in complex litigation
(...)
It reminded me of an old joke about the difference between a good lawyer and a bad lawyer, quoted here from a legal news website in Australia: “A bad lawyer can let a case drag out for several years. A good lawyer can make it last even longer.”