I respectfully concur in part, and dissent in part, in the result the majority reaches today.
1. Cartwright Act Action
I concur in reversing the order dismissing REI under the second cause of action because, as a result of the first MacManus appeal, it is law of the case *1118that a Cartwright Act action is stated whether or not AERP and REI operate as a single entity. The majority’s analysis of the impact of Copperweld appears to be dicta, which should await decision in another case.
2. Class Action
I respectfully dissent from the reversal of the order denying class certification.
It is law of the case that the case’s key issue (whether AERP required buyers to use the services of REI as a condition precedent to purchase) is a question of fact to be resolved at trial. (MacManus v. A. E. Realty Partners (1983) 146 Cal.App.3d 275, 284 [194 Cal.Rptr. 567].) I would hold that this requires separate proof as to each purchaser, precluding a class action. (Fletcher v. Security Pacific National Bank (1979) 23 Cal.3d 442 [153 Cal.Rptr. 28, 591 P.2d 51].) This case does not involve violation of a statute thereby precluding the need for individualized proof of lack of knowledge of fraud, as the majority suggests; on the contrary, this case demands individualized proof of the nonfraud, contract-making facts surrounding each purchase transaction.
Deference should be given to the trial court’s ruling denying certification. Trial courts are entitled to great discretion in the matter, and an appellate court should not disturb a ruling supported by substantial evidence unless improper criteria were used or erroneous legal assumptions were made. (Richmond v. Dart Industries, Inc. (1981) 29 Cal.3d 462, 470 [174 Cal.Rptr. 515, 629 P.2d 23].) Neither of those defects appears here. Substantial evidence supports the trial court’s decision, and it should be upheld.
On November 25, 1987, the opinion was modified to read as printed above. Respondents’ petition for review by the Supreme Court was denied February 4, 1988.
Assigned by the Acting Chairperson of the Judicial Council.