The court disagreed with Apple's suggestion that copyright misuse can only be used as a defense, and not as a counterclaim. "This order is unconvinced, however, that misuse may never be asserted as a counterclaim for declaratory relief," Alsup wrote in his ruling. "PsyStar may well have a legitimate interest in establishing misuse independent of Apple's claim against it, for example, to clarify the risks it confronts by marketing the products at issue in the case or others it may wish to develop."

The judge also alluded to the potential affects on other companies if the court rules in Psystar's favor. "Moreover, if established, misuse would bar enforcement (for the period of misuse) not only as to defendants who are actually a party to the challenged license but also as to potential defendants not themselves injured by the misuse who may have similar interests."

The unfair competition claims were rejected in part by the connection to antitrust laws, a stance that was previously denied by the court. "Plaintiff fails otherwise to identify an actual or incipient violation of antitrust laws or the spirit thereof - harm to competition," Alsup said.

A Psystar win could have a significant effect on the market for Mac clones. Despite Apple's aggressive legal actions, several other companies continue to produce similar products. EFI-X produces a dongle that allows Mac OS X to be installed on systems, although the company recently changed its US distributor to avoid marketing the device as a tool to create Mac clones. A German company, HyperMegaNet, recently began shipping clones with the operating system pre-installed.

Lawyers for Psystar are now required to submit the amended counterclaims, while Apple must provide an answer to within 20 days. "Both sides should be taking discovery and preparing themselves for trial and/or summary judgment," the judge said.