Serial killer Levi Bellfield has instigated a new law which has come into force today.
It rules that the most serious offenders cannot get married behind bars.
Bellfield abducted and murdered 13-year-old Milly Dowler on her way home in Walton in 2002.
He then killed Marsha McDonnell outside her home in Hampton in 2003 and Amelie Delagrange as she crossed Twickenham Green in 2004.
He also tried to murder 18-year-old Kate Sheedy in Isleworth in a hit and run.
He is serving two whole-life sentences and can never be released.
There was anger when the 56-year-old looked set to get married in prison after becoming engaged to a female visitor two years ago.
The move is believed to have prompted the government to speed up the introduction of the new law.