The issue of copyright has to strike a delicate balance between protecting the creators of music, words or photographs and the dissemination of such material to a wider public.
On the one hand, you want to ensure that the creators get paid for what they create. On the other, if copyright protection is too tight, then dissemination of material becomes too restricted.
In the 18th century the spread of knowledge was dependent on reprinting.
A book produced in London or Paris would be reprinted in Geneva, Edinburgh or Dublin.
"That led to arguments among publishers and authors about whether reprinting was immoral or illegal," says Adrian Johns at the University of Chicago.
The concept of intellectual property was based around the distinction between mechanical invention, and literary or cultural creation.
That idea is now less appropriate to the ways in which creativity is carried out - software development, biotechnology and gene science all conflict between the mechanical and the intellectual.
The advent of the internet has changed the way copyright works.
Under the previous technology, going into a shop and stealing a music CD was theft, and yet down-loading tracks from the internet seems un-theft-like.
This attitude, that if it is on the web then it is free, is even more pronounced with photographic images. When pictures were printed on paper it was easy to control, but new technology makes those old laws out-dated or at least difficult to enforce.
Track and control usage
The Magnum photo agency was founded in 1947 by some of the world's greatest photographers, including Henri Cartier-Bresson, to keep control over their own pictures.
Current member Stuart Franklin says: "We know exactly who is drawing photographs off our web site, we know who is downloading them and who has access to them."
He acknowledges that there will be some countries where people will get access to some of his work and says the pirating of photographs is similar to the pirating of music or movies.
"You can never control everything all of the time, but you can set up mechanisms that allow you to track and control usage," he says.
Stuart Franklin took the famous picture of the protester standing in front of the tank at Tiananmen Square - an image that has appeared on countless T-shirts around the world.
"We licensed my photographs to go on posters and T-shirts through business associates," he explains.
"The photograph itself is almost in the public domain, but if people want to use it to make a profit, such as a magazine or newspaper, then they have to pay," he says.
"We have no problem at all with dissemination and actively encourage students and young people to engage with our photography. What we don't encourage is pilfering for profit of our work."
There is a view that photographers should accept their work is going to be broadcast widely, whilst others say they should find technical means to stop copying.
Olivier Laurent of the British Journal of Photography says that sharing-sites such as Flickr or Facebook should be relished and used, although he maintains that people should be careful about how they use them.
"While I understand that photographers and industries want to protect their images they have to find another way to prevent people from sharing," he says.
"People who copy these images are thieves, but the industry as a whole has made it possible for people to do that very easily," he maintains.
"Twenty years ago you cut pictures out of a paper and put them on your wall - that would be stealing as well," he adds.
A few companies in Silicon Valley are working on ways for copyright information to be an integral part of the image which cannot be removed.
William Fisher at Harvard University thinks copyright protection is too strict, so, for example, works of art derived from photographs are blocked.
"There needs to be more creative freedom," he believes.
"The current system is over-protective. It extends copyright protection to too every snapshot, every digital image - billions are being created every minute all around the world and they are all protected by copyright law."
He acknowledges that a system is needed that affords protection to photographers who wish to have control over their work.
"But too much copyright protection impedes cultural conversations and cultural usage," he says.
He says there should be a change of bias when protecting work.
"It would be better if the photographer registered any image be wanted to protect with an online registration system," he says, "and that any other work was in the public domain."