Intervention: What is it? 

Dictionary definition:
To intervene is  
1) to come or be between as an action. 
2) to occur incidentally so as to modify a  result.
3) to come in, as something not belonging.

The Johnson Institute describes intervention as a process by which the harmful, progressive, and destructive effects of chemical dependency are interrupted and the chemically dependent person is helped to stop using mood altering chemicals and to develop new, healthier ways of coping with his/her needs and problems.

Working Definition: An Intervention is a way of presenting the reality of the addiction, in a caring way, by using specific facts and information, so that it can be heard  by the addict. Perhaps, even shorter and simpler is to say that intervention is presenting reality ina receivable wayto a person who is out of touch with their reality. An intervention mirrors back to the person the facts around his drinking/drugging behaviour.
The above implies that the person need not be an emotional or physical wreck (or hit bottom) before help is given. An intervention is a confrontation or challenge in which the person is compelled to face the facts about his or her chemical dependency. It is not punishment, nor is it an opportunity for others to clobber him or her verbally. It is an attack on the person's wall of defenses and denial, and not an attack on the person. An intervention is designed to let the person experience the "moment of truth" about himself or herself.

Some presuppositions.

1. Chemical dependency (alcoholism and drug abuse) is a disease.
2. We do not blame the chemically dependent person for being chemically dependent.
3. The people who have the disease generally do not seek treatment of their own volition because they do not think they have a problem.
4. The dependent person develops a delusional system that prevents him/her from seeing what is happening.
5. The whole family suffers from this disease. Spouses become co-dependent and children adopt roles.