Who Conducts The 730-Custody Evaluation?

The custody evaluation is conducted by a qualified mental health professional. The qualifications include having the right training and experience. Typically it will be a psychiatrist or psychologist, although some social workers and some Marriage and Family Therapists (MFT) also do them. Because psychiatrist's training does not include psychological testing, they are typically not qualified to administer, score, and interpret psychological tests. Most often a psychologist does that, because it is a regular part of their training. 

Some psychologists do their own psychological testing, while others will refer that portion of the evaluation to a professional who is experienced in psychological assessment. Similarly, an evaluator who is a psychiatrist will likely refer the testing to a psychologist. In this scenario, the family would undergo psychological testing by the testing professional. The job of that professional will be to describe the personalities and family dynamics, and alert the referring professional to any potential mental health or parenting problems. 

The testing professional is not supposed to make any custody/visitation recommendations. That job is left up to the referring evaluator, who is under obligation to the court. The evaluator will summarize their work, findings and recommendations and submit a written report.

In some jurisdictions, a "mini-evaluation" can be ordered. It is referred to as "mini" because it is less extensive than the typical evaluation. This may be requested to speed up things, or when the scope of the evaluation can be reduced such as when the court wants to know the answer to a particular question. 

Regardless of the type of professional doing the evaluation, that person is likely to be bound to professional standards of conduct and professional ethics. 

In the case of psychologists, especially if they are members of the American Psychological Association, they are held to the professional ethics (Ethical Principles of Psychologists and Code of Conduct (1992) and the Guidelines for Child Custody Evaluations in Divorce Proceedings.  Of course, these professionals are also bound by the Business and Professions Code. Another set of guidelines comes from the Association of Family and Conciliation Courts.