Pursuant to CPLR article 9, the trial court has considerable flexibility in overseeing a class action, and the court may decertify the class at any time before a decision on the merits if it becomes apparent that class treatment is inappropriate. Still, the proponent of class certification bears the burden of establishing the criteria promulgated by CPLR 901(a), and must do so by the tender of evidence in admissible form.
Mid Is. LP v. Hess Corp., NY Slip Op 03270 (1st Dep't June 11, 2020)
Here is the decision.
