Employers are heralding the U.S. Supreme Court's decision this week in Wal Mart Stores, Inc. v. Dukes, 564 U.S. __, No. 10-277 (June 20, 2011), which decertified a class of 1.5 million current and former Wal-Mart employees. Although the Dukes plaintiffs alleged gender discrimination, the Court's ruling will have broad impact, and advertisers should take note.

The Dukes decision offers advertisers new ammunition to oppose class certification in false advertising class actions. Here are three especially important aspects of the ruling to note:

• Common questions of fact and law do not justify a class action, unless those questions have common answers for all putative class members.

The Supreme Court recognized that with clever lawyering, almost any class action complaint can raise "common questions" of fact and law. Thus the existence of common questions, according to the Court, will not justify class certification. Rather, a class is appropriate only if the answers to those questions are common to all class members....