You can call it the anti-certification motion, the motion to de-certify, or a motion to strike class allegations. Some employers bring preemptive motions to head off plaintiffs' motions for class certification. That's a bold move that could stop a class action in its tracks. Or it could result in a denial that portends rough going when the plaintiff ultimately seeks certification.
BCBG is a retailer who was party to a wage and hour class action (exemptions) that lasted some three years before the company decided to bring matters to a head. The plaintiffs argued that there was no such thing as a motion to strike class allegations. But the court of appeal upheld the procedure here. The case is In re BCBG Overtime Cases.