(a) Courts may fashion equitable remedies in CEQA litigation. If a court determines that a public agency has not complied with CEQA, and that noncompliance was a prejudicial abuse of discretion, the court shall issue a peremptory writ of mandate requiring the agency to do one or more of the following:

(b) Following a determination described in subdivision (a), an agency or project proponent may only proceed with those portions of the challenged determinations, findings, or decisions for the project or those project activities that the court finds:

(c) An agency may also proceed with a project, or individual project activities, during the remand period where the court has exercised its equitable discretion to permit project activities to proceed during that period.

(d) As to those portions of an environmental document that a court finds to comply with CEQA, additional environmental review shall only be required by the court consistent with principles of res judicata. In general, the agency need not expand the scope of analysis on remand beyond that specified by the court.