This is why some ‘mental health professionals’ diagnose their clients with Borderline Personality Disorder – so that if the client accuses the therapist of any type of ethics breach, the therapist can defend themselves by saying, ‘the client has a history of lying/instability/etc and is just saying this because they didn’t like what I said to them’.
In reality, many women diagnosed with BPD have been pushed so far in abuse situations that acting out is the only way they can cope with the abuse that happened prior to seeing the therapist. (I say women because men with BPD tend to end up in prison rather than in treatment.) Saying that the client has a certain past doesn’t prove that they couldn’t possibly be victimized again by someone in a position of trust.