first I want to say the APA in your link is for the American Psychological Association which is different than the APA as in the American Psychiatric Association. Even though they both carry the same organization initials, they are two different organizations here in america that do completely different things in different ways. the first one over sees psychologists and the other is much bigger and publishes the DSM (diagnostic manual that says what mental disorders there are in america, the diagnostics and so on, and also governs things testing requirements and much more.)

how and what a treatment provider follows for court subpoenas depends upon each state and local organizations rules/ guidelines for it.

example here in my state treatment providers must answer the subpoenas by going to court and testifying under oath based on what questions the prosecutors and defending lawyers ask. its up to the lawyers to object when the other side is trying to breach confidentiality. if they dont object to the questions the witness (treatment provider) must answer the question just like any other witness that is under oath and testifying.

some mental health agencies purposely keep their files vague, (whittled down to just the facts ma'am so to speak) clients name, address, phone number, why they entered therapy, diagnosis, and a line or two that explains what all those session notes are.

example

Amanda Louise, phone number 234-234-2346 (obviously not going to post my actual name, address and phone number here lol)

Amanda louise entered therapy as a college class assignment in the fall semester.... after testing it was discovered amandalouise is diagnosed with.... ____, ____.___

she is being treated with medication, and therapy.

this weeks session focused on her PTSD symptoms.

signed (therapists name)

if my therapist got a court order handed to her she would have to per state law attend court and answer what ever questions the lawyers asked and it would be up to my lawyer to object to any questions that may breach my rights and confidentiality by making sure the questions being asked were about the crime not my history.

treatment providers must supply a rights and confidentiality information papers. it is ok to ask for them if you cant find yours that you have got or will get when you start therapy. these papers will tell you under what situations your treatment provider will have to disclose things from your files.