It is not only tech giants Apple and Samsung that are engaged in a series of legal battles over patent infringements. Two other major phone makers, Taiwan-based HTC and Finland-based Nokia have a court war of their own.

Over the weekend, the District Court of Mannheim in German court decided in favour of HTC in the patent infringement lawsuit Nokia brought against HTC over patent EP0812120 which is a method for using services offered by a telecom network, and patent 1312974 which describes a method to adjust the brightness of a phone's display in daylight and darkness.

HTC argued that Nokia exaggerated to coverage of the patent to get licensing royalties from makers of Android smartphones. It insisted the patent is not valid and vowed to pursue invalidity actions it filed with the English Patent Court and the German Federal Patents Court.

Nokia spokesman Mark Durrant said it disagreed with the court ruling and is studying its options over the decision. Nokia has 30 more patents that it has asserted against HTC in other lawsuits in Germany, the U.S. and UK.

Nokia also sided with Apple in the U.S. phonemaker's protracted legal battle with South Korean tech giant Samsung over six design patent infringements that involve the iPhone and iPad.

Nokia, once the top mobile phone maker until Apple released its iPhone and Samsung its Galaxy line, filed a legal brief with a U.S. court to support Apple's appeal to the court which denied the California-based tech firm's request to ban the sale of 26 Samsung gadgets in the U.S.

In denying the sale prohibition, the court said that Apple did not establishment consumer demand for Samsung products was because of the intellectual property that the South Korean firm allegedly stole from Apple.

Nokia, in its legal brief supporting Apple's stand, said patent laws are a means of developing technology for the benefit of consumers and pointed out the U.S. court ruling placed a very high benchmark to get an injunction. Nokia said the standards could hardly be met.

Ironically, Nokia was in a patent dispute with Apple in 2009 over the technical specifications of the iPhone.

Besides denying Apple's request to ban sale of Samsung products in the U.S., Judge Lucy Kho also cut by $450 million the damages awarded to Apple because of error by the jury in calculating the amount of award.

She also allowed a second Apple patent lawsuit against Samsung pending in her court over Apple's Siri technology. It is scheduled to go on trial in March 2014.

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