A federal judge in Camden, N.J., denied class certification Friday in a suit claiming reality TV star Bethenny Frankel falsely promoted her “Skinny Girl” margaritas as all natural.

The class can not be certified because the plaintiffs failed to meet the requirement under R. 23(b)(3) for ascertainability of its membership, U.S. District Judge Noel Hillman ruled in Stewart v. Beam Global Spirits & Wine, 11-5149. The lack of objective evidence to verify who bought the defendant’s product would force the court to conduct a “mini-hearing” on the merits of each case, the judge said, which would be unduly burdensome.