Consumers are confused by copyright laws that mean it is still illegal to copy a CD onto their computer, a watchdog says.
Consumer Focus said that copyright law was outdated and millions of people were unaware they were breaking laws.
But a legal expert has said that there was no danger of individual consumers being prosecuted for copying music and films for their own use.
Instead commercial operations are the focus of law enforcement.
The current state of the law means that it is illegal for somebody to copy a CD or DVD onto a computer or an Ipod for their own use. This copying to a different device is known as format shifting.
In a poll of 2,026 people, some 73% said that they did not know what they could copy or record.
Jill Johnstone, of Consumer Focus, called for the law to be updated to take the advance of technology into account.
"The world has moved on and reform of copyright law is inevitable, but it is not going to update itself," she said.
However, IT lawyer Nick Lockett, of DL Legal, said that nobody was being prosecuted for the technical breach in the law. Those who set up commercial operations were more at risk of prosecution, he added.
He said a similar issue arose when video recorders allowed people to record a television show and watch it later in the day - which at the time was illegal.
An amendment to copyright laws only came after video recorders had been on the market for some time.
One argument against allowing people to shift their music or films onto a different format was that the artists could claim that these works only had a limited lifespan and so people should pay them again for having the work on a different format.
Separate proposals to disconnect so-called peer to peer file-sharers has caused concern among internet campaigners.
This is when people share music or films even though only one of them has bought the original.