New legislation has given the police greater powers to clamp down on knife crime, sex offending and football hooliganism in Scotland.
The sentence for carrying a knife in public has been doubled
Justice Minister Cathy Jamieson said the act would allow officers to tackle the issues of greatest public concern.
The maximum sentence for carrying a knife will be doubled to four years and the age for buying a knife rises to 18.
There will also be extra powers to search the homes of sex offenders and to enforce football banning orders.
The Police, Public Order and Criminal Justice (Scotland) Act 2006, which comes into effect on Friday, also gives officers extended powers of arrest for those carrying knives in public.
For sex offences, officers have been given extra powers to enter and search the homes of offenders and to retrospectively ensure that a DNA sample has been obtained and filed from those convicted.
New football banning orders are aimed at tackling violence, sectarianism and racism. They can be also extended beyond football grounds to other flash points, such as pubs and train stations, lasting up to 10 years.
Ms Jamieson said the powers would be of huge benefit to police officers.
"In particular, the first provisions which will come into force from today, will provide them with new tools to address some of the areas which are of greatest concern to the public," she said.
"Scotland can be rightly proud of its excellent police service.
"I believe the new provisions will further help them meet the challenges of policing in a 21st Century Scotland - tackling crime and helping to create safer communities for all."