Editor's Note: (Robert Shore is editor of Elephant Magazine, a visual arts quarterly. This is an edited excerpt from his book "Beg, Steal and Borrow: Artist's Against Originality," published by Laurence King. )
(CNN) If you want to riff on the "Mona Lisa," go ahead. Scratch a biro mustache on her. Give her a full beard if you like.
Don't go drawing facial hair directly on the original, of course; that's the physical property of the Louvre, and the museum's conservators are likely to get very angry with you. But otherwise feel free to do your best or worst with Leonardo's portrait of Lady Lisa.
You can copy it or adapt it; you can even rephotograph it and Photoshop your signature on to it if you want. The original is out of copyright, and has therefore become part of the global creative commons.
If you use a photograph of the "Mona Lisa" as a basis for your art experiments and then try to sell the results, though, be aware that that photographic image may be separately copyrighted material. (Photographers have rights, too.) And it should go without saying that if you make an exact oil-on-board copy and try to pass it off as Leonardo's original, you may be charged with forgery. But otherwise knock yourself out. You are (almost, within carefully circumscribed limits) absolutely free.
If you want to do something with Pablo Picasso's "Les Demoiselles d'Avignon," on the other hand, you are much less free. Newsweek hailed it as "the most influential work of art of the last 100 years" in 2007, when it was precisely 100 years old, but just because it was likely made before your grandparents were born doesn't mean that it's in the public domain yet.
In fact, that hoary old museum piece "Les Demoiselles" will be in copyright for several more decades, because copyright's term has been extended considerably since Hogarth's day, when it ran from 14 years from the date of first publication. Now the formula is life plus 70 -- that is, until 70 years after the death of the author.
(The calculation is based on works providing for two generations of an artist's family after his or her decease; I wish my grandparents' pension plans had had similar provision.)
Had today's law been on the statute books in 1732, the copyright in Hogarth's "A Harlot's Progress" would have lasted until 1834 rather than 1746. That's a big difference. It means that if contemporary artists of an appropriative bent want to respond to work without worrying about copyright infringement, they should stick to stolidly 19th-century works: the Victorians are almost certainly out of copyright by now.
But you are very tightly restricted when it comes to playing with images created by other people or corporations in your own -- or indeed your grandparents' -- lifetime.
Ownership of a physical work of art can be transferred in perpetuity (sold), but even if you had personally paid $100 million for a painting by an artist who either was still alive or had died within the past 69 years, you would not have the right to exploit the work's image commercially; copyright would remain with the artist's estate.
For your $100 million you get the painting with all its attendant aura, but that doesn't mean you can stop the artist or the artist's estate from making the same sum again by authorizing the use of its image on supermarket carrier bags. Every groceries-shopper could have a copy for small change.
"Les Demoiselles d'Avignon," for instance, has belonged to the Museum of Modern Art in New York since the late 1930s; for nearly 80 years it has benefited from the physical and intellectual exertions of MoMA's conservators and curators.
But if you wanted to reproduce it in a textbook or use it as the basis for an artwork of your own, you would in the first place have to apply for permission to the Picasso estate, not to the museum.
And you might not get it: the makers of the film "Surviving Picasso" (1996) were denied the right to reproduce any of the Spanish master's works because the estate was reportedly unhappy with the script's portrayal of Picasso as a selfish womanizer. Messrs Merchant and Ivory had to make do instead with works by Matisse and Braque (whose estates did not object) to convey the period atmosphere.
Copyright is a cornerstone of any democratic, progressive, free society that values and wishes to continue to enjoy the benefits of a knowledge-based economy.
"As the founders of this country were wise enough to see," former register of copyrights Abraham Kaminstein told the United States Congress in the 1970s, "the most important elements of any civilization include its independent creators -- its authors, composers and artists --who create as a matter of personal initiative and spontaneous expression rather than as a result of patronage or subsidy. A strong, practical copyright is the only assurance we have that this creative activity will continue."
Most people agree that the world would be poorer without the works of Picasso, and in so far as his "creative activity" was supported by copyright, copyright must be a Good Thing.
But, you might ask, what is the "creative activity" of Picasso's estate? It is certainly not creative in the sense that Picasso was (its most famous, highly controversial "creative" act was putting Picasso's signature on a Citroën car), and yet it enjoys the same copyright privileges. Actually, it enjoys more: in Picasso's lifetime, copyright lasted only 50 years beyond an artist's death.
So copyright, in some measure, is a Good Thing. But, as your parents most probably told you the first time you came home drunk, you can have too much of a Good Thing.
"Beg, Steal and Borrow: Artist's Against Originality" by Robert Shore, published by Laurence King, is out now.