Oral argument took place in the Halliburton case earlier this week. The case addresses whether the Fifth Circuit's requirement that plaintiffs establish loss causation at the class certification stage of a case exceeds what is required by Federal Rule of Civil Procedure 23. The transcript of the argument can be found here.
The defendants faced an uphill battle: other circuit courts have rejected the Fifth Circuit's approach and the government also weighed in against the decision. As a result, the defendants argued that the real import of the Fifth Circuit's decision was not that the plaintiffs must establish loss causation (as that term is generally understood in securities fraud cases), but rather that the plaintiffs must establish that the alleged misstatements resulted in a "price impact" so as to allow for a presumption of reliance based on the existence of an efficient market. To the extent that the defendants can successfully rebut the presumption and demonstrate that common issues will not predominate, they should be able to do so at the class certification stage. As the the transcript strongly suggests, the key question for the Court will be whether the predominance analysis under Federal Rule of Civil Procedure 23 allows for this extensive an inquiry (as opposed, for example, to just requiring plaintiffs to generally show that the market for the company's securities was efficient).
For a summary of the oral argument, the D&O Diary has a comprehensive guest post. In addition, The Conglomerate Blog has an academic roundtable that does an admirable job of analyzing the various considerations before the Court and offers some predictions about the Court's eventual decision (hint: it will be narrow).