"Apple is attempting to use its copyrights in the Mac OS, not to prevent unauthorized production of any copyrightable elements, but to prevent competitors from developing competing hardware systems interoperable with the Mac OS," sausPsystar. "Through the use of anti-circumvention and the DMCA, Apple is attempting to leverage its copyright limited monopoly in reproduction of the Mac OS into a broader monopoly in a separate hardware market. This is the exact behavior that is prohibited by the copyright misuse doctrine."

Earlier this week it was reported that Psystar had modified its counterclaim against Apple to drop some of the riskier assertions of anti-competitive behavior, but has similarly added new sections that refute allegations of violating the DMCA.

Earlier this month Apple added new charges to the federal lawsuit it filed nearly five months ago against a Florida clone maker, claiming that Psystar broke antipiracy defenses that lock Mac OS X to its own hardware.

Apple also said others besides Psystar were involved, but it didn't spell out who. In a filing dated Nov. 26, Apple amended its original suit of July after it had "discovered additional information." Among the additions is a new accusation -- that Psystar violated the Digital Millennium Copyright Act (DMCA) by dodging copy-protection technologies Apple uses to protect Mac OS X, notes Computerworld.

Psystar -- which makes and sells Mac clones -- has claimed in the past that Apple has violated Sherman antitrust rules and other U.S. laws. Psystar claims in court documents filed in U.S. District Court for San Francisco that Apple “has engaged in certain anticompetitive behavior and/or other actions that are in violation of the public policy underlying the federal copyright laws.”

In response, Apple said the defendant, Psystar, “is knowingly infringing Apple’s copyrights and trademarks, and inducing others to do the same.” Psystar makes and sells personal computers that use, without permission, Apple’s proprietary operating system software.