The Garda file on three separate allegations of assault against the 43-year-old has gone to the Director of Public Prosecutions (DPP) for consideration.
The file contains allegations of assault by the singer against Aer Lingus flight attendant Carmel Coyne, a garda and an airport police officer (APO) at Shannon airport on November 10.
It is alleged that The Cranberries singer — who has been diagnosed with bipolar disorder — spat at both the Garda and APO.
The file was sent to the DPP by Clare gardaí last week. Due to the lack of complexity in the case, gardaí expect a recommendation from the DPP as to whether or not to prosecute Ms O’Riordan before the Christmas break.
If the case does go to court, Ms O’Riordan’s mental state during the incident is expected to play a key role in her defence.
It is alleged the mother of three was taken from the Aer Lingus aircraft by airport police and that she pushed, hit into the chest, and spat at one of them.
Gardaí were called and it is further alleged that Ms O’Riordan hit one garda in the face and body and also spat in his face.
The file contains statements from around 12 witnesses.
If the DPP does decide to prosecute Ms O’Riordan, it will be most likely for Section 2 Assault under the Non-Fatal Offences Against the Person Act 1997.
Those convicted of such an offence — regarded as a minor assault — can face penalties of a prison term up to six months or a fine not exceeding €1,900 in the district court.
Ms O’Riordan has been unavailable to gardaí and her mother last month said she has been under the care of a psychiatric doctor.