The court took on three class action cases last year, Himmelfarb noted, and decided two of them for the plaintiffs, one unanimously.

FORBES: Class-Action Lawyers Face Triple Threat At Supreme Court

But Himmelfarb said defense lawyers in Amgen will argue their case merely seeks to establish the conditions required to establish fraud on the market.

FORBES: Class-Action Lawyers Face Triple Threat At Supreme Court

That put the Ninth in the familiar position of being in conflict with the First, Second and Third Circuits, according to Mayer, Brown attorney Dan Himmelfarb.

FORBES: Supremes Smell A Live Issue in Zicam Case