Alsup's ruling is similar to one made by an appeals court in the mid-1990s, which found "that the menu command structure of [the software program] Lotus 1-2-3 was original and creative, but that it was not copyrightable because it was also a method of operation," Ochoa added. "Although that was something of a controversial ruling at the time, it has widely come to be accepted law, and I would be astonished if the Court of Appeals or the Supreme Court would take issue with it now."

Moreover, Oracle will not only have to convince the appeals court Alsup was wrong, but also "persuade a jury on retrial that the use was not a fair use" under copyright law, Ochoa added. "Oracle can continue pouring money down this sinkhole if it wants to, but it would be well-advised to concede defeat now."

Prior to Alsup's ruling Thursday, a jury cleared Google of patent infringement in the case.

(James Niccolai in San Francisco contributed reporting to this story.)