New sentences for knife crimes in England and Wales
3 December 2012 Last updated at 13:53 GMT
Several new criminal offences and sanctions come into force in England and Wales today, including new tariffs for some knife crimes.
A new offence of aggravated knife crime is among the measures being brought in, as well as mandatory life sentences for anyone committing a second serious violent or sexual offence.
Also introduced by the government are "Extended Determinate Sentences", when offenders must serve at least two-thirds of their prison term.
The BBC's legal correspondent Clive Coleman reports.