More than half of British consumers are infringing copyright law by copying CDs onto other players they own, according to the National Consumer Council (NCC).
Only 19% knew copying CDs was illegal, according to the poll
In an online poll of 2,135 UK adults conducted by YouGov, 55% said they copied CDs onto computers, iPods, MP3 players and other equipment.
Three in five of those questioned - 59% - thought it was legal to do so.
The NCC said their findings showed the law is out of step with modern life and discriminated against consumers.
"We need to shake up the copyright law to incorporate the right to copy for private use," said the NCC's Jill Johnstone.
The organisation is also opposing a campaign by the UK music industry to extend the time musicians receive royalties for their work.
"The current campaign to extend copyright terms for sound recordings beyond 50 years has no justification," said Ms Johnstone.
"Evidence shows music companies generally make returns on material in a matter of years, not decades.
"Current terms already provide excessive protection of intellectual property rights at a cost to consumers."
The Treasury has appointed Andrew Gowers, the former editor of the Financial Times newspaper, to conduct a review of copyright and intellectual property policies in Britain.