The therapist has complete control over the sessions and the client has to do what the therapist tells him/her to do. The reason being is that the client has no control over his/her life and that is why they do go to this type of therapy, they need to change their way of thinking in order to get out of the mess that made them go in the first place. It is like being addicted to methadone. In order to get clean they have to first dry out from the drug and then while drying out they have to do a complete 360 of their thinking process so that they do not fall into the same trap again.
Cognitive behavioral therapy is very effective therapy but has a potential draw back in it. As it has been criticized that therapist has a very directive dealing with client and all the therapy is based on the therapist instructions and directions. No client's personal involvement is taken much in account.