Watch Rob Murphy's report
A new central register is being set up to make it easier to check up on taxi drivers after the murder of a 22-year-old woman from Wiltshire.
Sian O'Callaghan was killed by taxi driver Christopher Haliwell, who picked her up as she left a nightclub in Swindon on March 19, 2011.
Her disappearance sparked a major investigation by Wiltshire Police and her body was found five days later in a shallow grave near to the famous White Horse pub in Uffington, Oxfordshire, having been taken there by Halliwell.
Halliwell was later handed a whole life order after being convicted of murdering a second woman, Becky Godden.
Following his sentence, police said there is a “distinct possibility” Halliwell is a serial killer, highlighting the eight-year gap between the murders.
Now Sian's family have welcomed the introduction of a new law - dubbed Sian's Law - which has come into place 11 years after her murder.
Sian's mother Elaine Pickford told ITV West Country: "There's no situation where you are more vulnerable than being a person on your own getting into a vehicle with effectively a complete stranger, so that needs to be as secure and as safe as can be."
It has taken four years of campaigning to get the new law introduced, with the family supported by The Suzy Lamplugh Trust to get it through.
What is Sian's Law and how does it work?
Sian's Law will mean reports and complaints will be logged on a national database which all authorities will have access to.
"They will be required to take that information into account when granting licensing for drivers," said Saskia Garner, from the trust.
While they are pleased with the result of the campaign, Sian's mother and brother, Liam, want it to go even further - with CCTV made mandatory for all taxis and private hire vehicles.
Liam said: "Its an honour to know that Sian's name is being used in a positive way and that she has a legacy of protecting other passengers."