A fierce debate about an academic theory loomed over the Nobel in economic science for 2013. Last week, the Supreme Court enshrined that argument in jurisprudence, issuing a ruling that is likely to make it harder for investors to prevail in some big class-action lawsuits.

The court’s decision emerges from a debate that has been simmering among economists for decades. It flared up again last fall, after the Nobel committee announced that it was giving the 2013 prize to three economists with discordant views on a wonky notion known as the efficient-markets hypothesis. Its core tenet is that market prices embody all available information. That may seem a simple thought, but its implications are controversial, and the court’s position has important repercussions.

The court delved into this arcane issue during a busy week in which it issued a series of major decisions dealing with cellphone privacy, presidential recess appointments and broadcasters’ copyrights in a dispute involving Aereo, the upstart television streaming service.

It turned to the efficient-markets hypothesis in a case concerning asbestos liabilities of the oil services company Halliburton. The court rejected a broad challenge to class-action lawsuits contending securities fraud. But it added a major new hurdle for investors that could stop some class-action suits in their tracks by letting corporate defendants try to prove, at an early stage, that there was no connection at all between corporate misstatements and share prices — and therefore no grounds for litigation.