How European Arrest Warrant plays vital role in war on crime
The European Arrest Warrant - which came into force in 2004 - was designed to remove much of the red tape and international brinkmanship from the extradition process.
It allows for faster and simpler surrender procedures and an end to political involvement in extradition procedures, according to the European Commission.
After its introduction, EU countries could no longer refuse to surrender their own citizens to another European Union country, if the citizen has committed a serious crime or is suspected of having committed such a crime in another EU country. The arrest warrant is valid throughout all EU member states.
From 2010-16, the PSNI issued 50 EAWs, with only the Met and Greater Manchester Police issuing more.
In that same period, the Irish Republic detained 195 people under an EAW, although only two for terrorism.
The EAW is viewed as particularly useful in Ireland north and south, ending the long-running extradition battles of the past.
Recently, it was used to detain Hungarian national Beres Szaboles (28) after he seriously injured a young women in a car crash in Ballynahinch in 2015.
Before he was initially charged, Szaboles fled Northern Ireland but was detained in Copenhagen under a European Arrest Warrant. He will be sentenced next month. And earlier this year, a former INLA member wanted for a murder in Co Tyrone almost 20 years ago lost a legal challenge to being extradited from the Republic.
The authorities here had been seeking the surrender of Francis Lanigan (53), originally from Belfast but with an address in west Dublin, for the murder of John Knocker, who was shot dead in Dungannon in 1998. In 2013, Lanigan was arrested on foot of an EAW at a Dublin gym where he was working as a barber.
Before the EAW, extradition cases in Ireland were characterised by long-running legal and political battles.
From 1973-97 the UK sought the extradition of 110 republican suspects from the Irish Republic, but just 42 were arrested and only eight were extradited.
In March 1990, the Supreme Court of Ireland in Dublin blocked the extradition of Maze escapers James Pius Clarke and Dermot Finucane on the grounds they "would be probable targets for ill-treatment by prison staff" if they were returned to jail in Northern Ireland.
In 1988, a UK request to have suspected IRA quartermaster Fr Patrick Ryan extradited from Belgium failed. He was later extradited to the Republic, but it refused to extradite Ryan to the UK - causing a rift between Prime Minister Margaret Thatcher and Taoiseach Charles Haughey.