Psystar continued the holiday cheer last week with an amended filing that accused Apple of improperly handling its copyrights.

Apple "is prohibited from bringing action against Psystar for the alleged infringement of one or more of [Apple's] copyrights for failure to register said copyrights with the Copyright Office," according to a Dec. 16 document.

Psystar also accused Apple of misusing its copyrights by only allowing the Apple OS to be installed on Apple machines.

Apple "has attempted to (and continues to) leverage the rights granted under any valid copyright to areas outside the exclusive rights granted by the Copyright Act [by] forcing purchases of Apple-Labeled computer hardware systems," according to Psystar. "Apple has thus engaged in certain anticompetitive behavior [by failing] to abide by the fair use and first sale doctrines."

Apple sued Psystar in July for copyright infringement, breach of contract, trademark and trade infringement, and unfair competition after Psystar started selling the Open Computer, which uses a modified version of Apple's OS X. Psystar responded, charging Apple with violations of various antitrust laws, but a federal judge tossed out Psystar's antitrust defense last month.

Apple is improperly claiming that installation of the Apple OS on a non-Apple machine is a violation of the Digital Millennium Copyright Act (DMCA), according to Psystar.

"By attempting to apply the DMCA in this manner, Apple is attempting to obtain, maintain, and/or enjoy rights not granted by the Copyright Act," Psystar said. "Apple does not actually employ a technological copyright protection measure that effectively controls access to the Mac OS."

Apple is only using the threat of the DMCA to "chill innovation" and prevent third parties from the "legal and legitimate development of products that compete with Apple-labeled computer hardware systems."