A UK consumer watchdog has called for new laws to protect users' rights to use digital music and movies.
Consumers are being frustrated by digital locks on music and movies
The National Consumer Council (NCC) said anti-piracy efforts were eroding established rights to digital media.
The NCC had little faith that industry self-regulation would adequately protect consumers' rights.
It made its comments to a parliamentary inquiry into technologies that limit what people can do with CDs, DVDs and downloaded media.
In its submission to the inquiry, the NCC said many consumers were regularly running up against the restrictions record companies and film makers put on their products.
The consumer group said people were finding that they could not make compilations for their own use or easily move digital copies between different devices.
In its statement to the inquiry it said the digital locks put on content were "constraining the legitimate consumer use of digital content".
Also being undermined were rights established by consumer protection and data protection laws, it said.
"Consumers face security risks to their equipment, limitations on their use of products, poor information when purchasing products and unfair contract terms," said Jill Johnstone, the NCC's director of policy.
She added that the group had little faith that self-regulation by media makers would protect consumer rights.
As a case in point, the NCC referred to the furore over the methods Sony BMG used to stop some of its CDs being copied.
The music maker suffered a long bout of bad publicity following the discovery that its anti-piracy system used virus-like techniques to hide itself.
The row led to Sony BMG being sued by many consumers and many US states. Eventually Sony recalled the CDs using the most controversial anti-piracy software and offer refunds to consumers who suffered.
It has also stopped using some copy protection systems following the row.