As a recovering junkie, everything is a choice...I am possibly not the most sympathetic addicted person around though, cause I think 'starving people' in 3rd world countries have a choice too...they could always go throw themselves off a cliff.
Personally, I think the catch 22 of choice is not so much whether or not addicts have the choice to avoid, start or stop using - even if physically addicted - but its the good ole argument about free-will vs human nature.
I am not a believer in the concept that addiction is a disease...I really don't care what science has identified, they could start classifying anything socially undesirable as a "disease" (actually, we do). And I have first hand experience, being a heroin addict for 17 years...it was always a choice.
As for research links, good luck. Now that drug addiction has publicly infiltrated the middle class, social dogma relieves responsibility for ones actions as a matter of PC...Try delving into either the philosophical or even theological areas. (ex. free-will = choice, but human nature = self-indulgence...so, is it possible to deny human nature (self indulgence) and still be human enough to exercise free-will? or, are we just doomed from the get go and drugs are just a single element of our eternal struggle).