The maximum sentence handed down to those convicted of assault has been doubled after new justice powers agreed by the Assembly became law.
People found guilty of common assault or battery in Northern Ireland could now face up to six months behind bars rather than the previous limit of three.
Under the terms of the Northern Ireland Justice Act 2011, the authorities also have wider powers to deal with sex offenders who breach the terms of their release licence.
Provisions to enable vulnerable or mentally unwell offenders to appear in court via videolink were also introduced as part of the Act, as were powers to monitor criminals' financial affairs.
The changes coming into effect represent the first tranche of the act, with further law changes set to be introduced later in the year.
Next month, legislation to create new public-order offences at sports events to help control the behaviour of violent or abusive fans will be placed on the statute.
The provisions are the first justice powers debated and agreed by a devolved Stormont administration since the early 1970s.
Justice Minister David Ford welcomed the changes.
"These new provisions flow from the first justice legislation to be passed by the Assembly in over 40 years and are an important part of my programme to reshape the justice system," he said. "The passage of the Justice Bill was an important milestone following the devolution of these powers to the Assembly.
"I remain committed to bringing forward the reforms that are necessary to improve our justice system and build a safer, shared society for all the people of Northern Ireland."