Apple has launched a second lawsuit and a trade complaint against competitor Creative Technology.
It's the next twist in the increasingly bitter battle between the two firms, which fight furiously for market share in the MP3 player market.
Creative launched legal action against Apple last month, alleging the California firm had abused its patent for a hierarchical menu-based navigation system for music players.
The company also asked the US International Trade Commission (ITC) to investigate whether Apple has violated US trade law by importing the players into the US, a move that eventually could halt iPod sales in the US.
Apple immediately launched a countersuit in a Wisconsin court, and has followed this up with a new lawsuit which it filed in a Texas court last Thursday.
Apple's latest legal salvo accuses Creative of infringing three patents: one involves the display of data on a computer, another relates to editing data using a portable media device, and a third describes the creation of icons to organise files on a computer.
Apple is suing for cash damages and a court order to stop Creative from further breaches of its patents. Apple has also asked the ITC to intercede. Apple wants the ITC to block imports of Creative's music players on the grounds of the patent abuse.
The decision to launch action in the Texas court may be a tactical move. A Reuters report cites 'legal experts' who say: "Patent trials put before juries in the court have favoured patent holders, suggesting that Apple has chosen the venue as a means to put pressure on Creative to settle the patent dispute quickly."
Analysts meanwhile have warned that Creative is unlikely to prevail in its new litigation challenge, and that engaging in the venture may cost its management time that the company should be using to focus on returning to profitability.Thoughts on patents and trademarks? Please comment in the Macworld Forum.