A woman from Weston-super-Mare claims the Home Office has failed to close a legal loophole that makes it easier for convicted paedophiles to re-offend.
A young relative of hers was molested by sex offender James McAlpine who had changed his name to avoid detection.
She says promises of new legislation after his conviction at Exeter Crown Court in 2002, have come to nothing.
The Home Office said it was working to "strengthen arrangements for dealing with sex offenders in the community".
Tennis coach McAlpine, from Exeter, Devon, should have been supervised by police after signing on the Sex Offenders Register - but he changed his name by deed poll to Jay Powers.
The woman from Weston-super-Mare, who cannot be named for legal reasons, said she became suspicious of him within a short while of meeting him. She later made enquiries to try to find out more about him, but drew a blank as he had changed his name.
McAlpine admitted 12 sex charges including a serious sex assault on a 13-year-old boy. He was sentenced to life in prison.
Following the trial, the Home Office said it had undertaken to look at the issue of deed polls with a view to legislation as soon as possible.
After criticism of inaction more than four years on, it says a comprehensive and thorough review of child sex offenders - commissioned last June - is continuing.
"This review is ongoing and involves regular contact with a wide-range of stakeholders including victims' groups, the NSPCC, Kidscape and those agencies working in the child protection field," said a Home Office statement.
"We are listening to the views of all those involved as part of the continuing work to protect children from sexual abuse.
"Through Multi-Agency Public Protection Arrangements (MAPPA) we have already revolutionised how child sex offenders are managed in the UK and now we want to look carefully at how we can build on and strengthen these, and other, arrangements."