Mandatory life sentences for those who kill an emergency worker in the course of their duty will be introduced by the government.
Known as 'Harper's Law,' the bill has received Royal Assent, which occurs when the Queen agrees to make a bill into a law.
It is given once a bill has completed all the parliamentary stages in both houses.
Lissie Harper campaigned for the law after her husband, PC Andrew Harper, was killed while he responded to an attempted burglary.
PC Harper, 28, died from his injuries when he was caught in a strap attached to the back of a getaway car in Sulhamstead, Berkshire, in August 2019.
He was dragged down a winding country road as his teenage killers fled the scene of a quad bike theft.
Henry Long (19), Albert Bowers (18) and Jessie Cole (18), were jailed for manslaughter.
Getaway driver Long received a 16 year sentence, while Bowers and Cole were handed a 13 year jail sentence.
Ms Harper said her campaign came about through a "journey of devastation and realising that our emergency services don't get the protection that they need".
'Harper's Law' means those who assault police or other emergency workers will see the maximum penalty doubled from 12 months to two years.
This includes frontline health workers, prison officers or fire service personnel.
The Act will also place a legal duty on local authorities, police, criminal justice agencies, health and fire and rescue services to work together to reduce serious violence.
It is one of four major bills that have become law, as part of the Police, Crime, Sentencing and Courts (PCSC) Act.
Lissie Harper, 31, said she intends to move forwards and effectively retire from public life when Harper's Law makes it onto the statute books.