[4][5] The Garda ERU 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.

[1][7][13] Garda officers had earlier conducted a study tour of the special units of the German Federal Police GSG 9 and Belgian Gendarmerie Speciaal Interventie Eskadron (SIE).

[14] On 17 March 1984, Special Task Force detectives captured Dominic McGlinchey, then considered leader of the Irish National Liberation Army (INLA), at a house in Newmarket-on-Fergus, County Clare following a gun battle in which an officer was seriously injured.

[21] An officer's journey into the ranks of the ERU begins with a notorious two-week initiation dubbed "hell week", where candidates are both physically and mentally assessed.

Failure during the recruitment process is extremely high (95%), but those who complete the tests successfully are then put through a number of more specific, rigorous exercises, where their suitability for the unit is determined.

[23] ERU officers are required to qualify three times per year for all firearms being used by the unit, complete regular fitness tests and psychological examinations.

As part of their training, each member of the squad is made to sample the impact of their own non-lethal weapons, including being subdued by a Taser and must perform tasks after being hit with pepper spray in the eyes.

Members of the ERU train regularly alongside Regional Support Units (RSU), the Army Ranger Wing and Explosive Ordnance Disposal (EOD) teams in Ireland, and abroad with; the Police Service of Northern Ireland (PSNI) Special Operations Branch (SOB) and Metropolitan Police Service (MPS) Specialist Firearms Command (SCO19) in the United Kingdom, and FBI Hostage Rescue Team (HRT) in the US, as well as similar organisations in France (RAID & GIGN), Germany (GSG 9), Netherlands and Finland.

[26] While the ERU armoury includes dozens of firearms, the standard issue pistol is the self-loading 9mm SIG Sauer P226, which officers carry on and off duty.

In addition to firearms, ERU operators carry routine police equipment such as a knife, ASP baton, pepper spray, flashlight and handcuffs.

[27][28][29] The ERU trains with other Garda units and the Air Corps in the utilisation of helicopters (AgustaWestland AW139 and Eurocopter EC135) and rigid-hulled inflatable boats (RIB), and has quick access to these when required.

[22] Legislation passed in Ireland in the aftermath of the November 2015 Paris attacks allows the Garda Emergency Response Unit to respond to a terrorism crisis in another country in the European Union, and for Gardaí to request assistance from foreign specialist forces.