730. When it appears to the court, at any time before or during the
trial of an action, that expert evidence is or may be required by
the court or by any party to the action, the court on its own motion
or on motion of any party may appoint one or more experts to
investigate, to render a report as may be ordered by the court, and
to testify as an expert at the trial of the action relative to the
fact or matter as to which the expert evidence is or may be required.
The court may fix the compensation for these services, if any,
rendered by any person appointed under this section, in addition to
any service as a witness, at the amount as seems reasonable to the
court.
Nothing in this section shall be construed to permit a person to
perform any act for which a license is required unless the person
holds the appropriate license to lawfully perform that act.
Things to know about a 730 evaluation:
In California, a child custody evaluation or "730 Evaluation", can be described as an in-depth study and analysis of the "family, it’s members, and/or prospective members", and their relationship. The evaluation is carried out by an "evaluator" with the intent of determining a family structure that would be in the "child's best interest."

There are three ways the 730 evaluation process can be started:

1) A judge can order both parties to submit to one.
2) One side may request one (said request subject to approval by the judge)
3) By stipulation, meaning both parties agree to it.

Selecting an Evaluator:

The evaluator can be a licensed clinical psychologist, licensed psychiatrist, Marriage and Family Therapist (MFT), Marriage, Family, and Child Counselor (MFCC), or Licensed Clinical Social Worker (LCSW).
1. The judge may chose the evaluator from a list the court maintains
2. The judge will ask the parties to submit a list of acceptable evaluators from which he or she will choose
3. With the help of the attorneys in the case who know various evaluators and their reputation in the community, the two sides will mutually agree on an evaluator
Four basic parts of an evaluation:
Written or Verbal Testing
Interview with both parents together
Interview with each parent
The children Interviewed with each parent