The School District was ordered to desegregate pursuant to a ruling in Crawford v. Board of Education. The desegregation plan was submitted to the superior court on March 18, 1977, and the issue of its adequacy was litigated. Bustop (P) a nonprofit corporation petitioned for leave to intervene in the action pursuant to section 387 of the Code of Civil Procedure. P is a membership organization with over 65,000 parents who are predominately white. The prime objective of P is to prevent mandatory reassignment of students to schools other than those which they now attend or choose to attend. P's petition was denied. P petitioned for a writ of mandate to compel intervention.