Psychotherapy is a private process that often involves discussion of very sensitive issues.  Most therapy clients assume that the things that they say to their therapist are completely confidential.  This is usually true, but there are exceptions.  Some of the exceptions may surprise you.

• Most people are aware that confidentiality can be broken if the client is believed to be a danger to him or herself or someone else.  A psychologist or other mental health professional may be required to break confidentiality in order to protect the client or the person that they are threatening to harm.
  
  
• Most states in the United States require a therapist (or other professional) to report suspected child abuse.  Many other countries have similar rules.  The details of this reporting are usually spelled out in the law.
  
  
• A court can compel a therapist to testify about what is discussed in therapy.  This is not often done, but most ethics codes state that therapists are required to follow court orders.
  
  
• When your lawyer introduces your state-of-mind in a trial, your therapy records may then be an open book at the trial.  A recent court ruling upheld this principle.  
  
  In Sanchez v. USAir, U.S. District Judge Clifford Scott Green ruled that a plaintiff's psychotherapy records must be turned over to the defense whenever the plaintiff is pressing a claim for emotional distress -- even when the plaintiff insists that the therapy was totally unrelated to his or her lawsuit and that the therapist will not be called as a witness. According to Green: 

To allow plaintiffs to make a claim for emotional distress, but shield information related to their claim, is similar to shielding other types of medical records. For instance, if the injury at issue were to the knee, and plaintiff had sustained a subsequent knee injury requiring treatment, plaintiffs would not be able to hide the details of the subsequent knee injury because of privilege or privacy considerations. (Green, 2001, Sanchez v. USAir)

• Your therapy records may be a part of a larger medical record.  If treatment occurs within a large healthcare system, then all therapy notes may be available to any health provider treating you for any purpose.  This is true at the Veterans Health Administration in the United States, for example.  As electronic medical records become more common the availability of this information may increase.
  
  
• Your insurance company often gets detailed information on your therapy.  At one time they only received basic information, such as diagnosis.  As managed care became popular in the U.S. the "care managers" have demanded more and more information about therapy.     

The Clinton administration passed sweeping U.S. federal medical records confidentiality rules before president Clinton left office.  The rules have not yet gone into effect, and the Bush administration is promising to rewrite them.  Until these rules get finalized the regulations regarding psychotherapy confidentiality vary from jurisdiction to jurisdiction.  In most cases your written permission is required for your therapist to send copies of notes to any third party except for the above exceptions.  

Psychologists and some other therapists are also required to inform their clients about the limits to confidentiality.  Ask your therapist if you are not sure who else gets information about your therapy sessions.