Our interventionist told us that the most important purpose of intervention was to start the family on the road to recovery...that the measure of "success" was not whether the addict chose to go to treatment, or to stay sober, but to change the family dynamics.
To this end, he had us call all my son's aunts and uncles and ask them to participate in the intervention. This required us to share information we'd been hiding - it was difficult, but brought our "secrets" into the open.
He then had us all participate in a one day educational session about addiction and the role of the family. It made sure we were all on the same page, and gave us a common language...bringing us together. Having the extended family participate helped ensure we would have support.
We had the intervention the next day - my son ran - but after 12 hours decided to accept the offer of treatment.
The interventionist stayed with us until the flight the next day, and flew with my son to treatment.
They then continued to support us, having us a write a letter after two weeks informing my son that he needed to be sober for a year before he could live at home, and worked with us to find an extended care facility.
My son did not really "buy" into treatment as a result of the intervention. He went to treatment, and the extended care facility, but started using again after about 5 months...but the intervention definitely was the turning point for ME in my recovery. We had sent our son to treatment once before- when he was 16 - but without the assistance of a professional interventionist, and at that time MY behavior didn't change. This time it did.
For our family, intervention was the right thing to do.