Special Detective Unit (SDU)

The Special Detective Unit (SDU) is the main domestic security agency of the Garda Síochána, the national police force of Ireland, under the aegis of the Crime & Security Branch (CSB). It is the primary counter-terrorism and counter-espionage investigative unit in the country. The Special Detective Unit superseded the Special Branch which they are still commonly referred to as. They work in conjunction with the Defence Forces Directorate of Military Intelligence – Ireland's national intelligence agency – on internal matters. The unit's headquarters are based in Harcourt Street, Dublin City.

The Special Detective Unit operates out of the Dublin Metropolitan Region (DMR) Headquarters of the Gardaí in Harcourt St, Dublin, and has personnel in all six Garda regions. The unit has a number of secret buildings in Ireland, which it uses for covert operations. The SDU has a strength of between 200 and 300 plainclothes detectives, and a further 100 officers attached to the Emergency Response Unit. The SDU is a highly secretive organisation that does its utmost to stay out of the media spotlight, and when officers from the unit appear in court they routinely give evidence anonymously from behind a screen to protect their identity. All officers within the unit carry firearms, and train more often than regular police detectives. All agents are armed with concealed semi-automatic pistols, and if the situation requires, they have access to shotguns, submachine guns, assault rifles and sniper rifles. The SDU has a large pool of unmarked and armoured cars, and has access to helicopters if needed.

GARDA EMERGENCY RESPONSE UNIT

The Emergency Response Unit is the premier armed tactical operations unit of the Garda Síochána, the national police force of Ireland. The Garda ERU is a section of the forces' Special Detective Unit (SDU). The unit provides the highest tier of firearms response to Irish law enforcement, specialising in weapons tactics, counter-terrorism, execution of high-risk missions, crisis negotiation, hostage rescue and close protection, among other roles. The ERU regularly trains with the Irish Army Ranger Wing (ARW), the country's military special operations forces, sharing facilities and equipment. 

OPERATIONS

The Special Detective Unit works closely with other specialist and national units within the Garda Síochána, namely the National Surveillance Unit (NSU) – a police intelligence gathering agency. The Special Detective Unit works with the Bureau of Fraud Investigation (GBFI) in relation to financial intelligence and terrorism financing. The Defence Forces Directorate of Military Intelligence – Ireland's national intelligence agency – shares intelligence, trains with and carries out joint operations with the unit. The SDU has historically operated in tandem with British, American and other European law enforcement agencies in combating terrorists and foreign government threats. They maintain a strong working relationship with the Police Service of Northern Ireland (PSNI), London Metropolitan Police Service (MPS), British Security Services (MI5) and the Federal Bureau of Investigation (FBI), among others, and share information with Europol and Interpol.

In 2010, the Special Detective Unit, Garda Bureau of Fraud Investigation (GBFI) and Criminal Assets Bureau (CAB) broke up what was described by Europol as "one of the biggest and most sophisticated counterfeiting operations ever uncovered in Europe", which had the capacity to produce €200 million (£167 million/$276 million) in counterfeit banknotes annually, some of which were shipped as far away as Japan, in an attempt to fund IRA terrorist and criminal activities.