Some, a minority, of people never really trust the confidentiality agreement, and I do not ever really get the full story. For others there is an element of resentment at having to attend and a constant fear of being breached. These added issues are obviously not present for voluntary users of the project. Some have agreed to the condition purely to avoid a prison sentence and if they do attend subsequently, they are more interested in getting away than talking about themselves. On the positive side for those people who are chaotic and who want help, the boundaries set by the court order can be extremely useful in providing a structure by which individuals feel supported.
Individuals vote with their feet ultimately.
Those who are breached and returned to court are, at worst, likely to receive the sentence they would have got if the scheme hadn't existed in the first place. Although attendance may as the result of some coercion for many clients it is the first time they have been in contact with a drugs service. Success for one will not necessarily be important for another. Convincing someone to regularly use the needle exchange will not necessarily be a Crown Court judge's first priority. Probation and the courts want to know the underlying issues that lead people to offend are being addressed in a way that can be reported back successfully.