Amnesty International has criticised the Garda Siochána for its use of "lethal force" in April 2000 when Longford man John Carthy was shot dead outside his home in Abbeylara Co Longford.
In its annual report published today, the human rights organisation also said "a series of command failures by police scene commanders" during the 25-hour long siege had led to the 27-year-old man's death.
Amnesty International said it "severely criticised police systems, management and training in dealing with mental health emergencies in the community and the use of lethal force".
"Insufficient precautions were taken to avoid or minimize the risk to life," it said. Mr Carthy was suffering from depression at the time of his death.
It was also found that Mr Carthy "was probably subjected to physical abuse while under interrogation" while in custody on a separate occasion in September 1998, and said that "investigations into this matter were inadequate".
The report into global human rights records for 2006 also found that Ireland "inappropriately" continues to admit children into adult inpatient mental health units, with up to 300 children currently living in these facilities.
It also highlighted the naming of Ireland as one of the states responsible for passive collusion in the US-led programme of secret detentions and renditions during the so-called "war on terror".
Other areas of concern raised by the Amnesty report were human trafficking and children's rights.
Amnesty expressed concern over legislative proposals to reform immigration legislation, published last September. It said the proposals highlighted an absence of "specific protection measures for victims of trafficking".
It said Ireland had failed to fully implement recommendations by the UN Committee on the Rights of the Child to adopt a child rights-based approach in Government policies.
Amnesty said it was specifically concerned at Ireland's failure to incorporate the UN Children's Convention into domestic law.
On a global level, the report said it was concerned that "powerful governments and armed groups are deliberately formenting fear to erode human rights and to create an increasingly polarized and dangerous world".
Noeleen Hartigan, Programmes Director at the Amnesty International Irish Section said: "Through short sighted, fear-mongering and divisive policies, governments are undermining the rule of law and human rights, feeding racism and xenophobia, dividing communities, intensifying inequalities and sowing the seeds for more violence and conflict".