There are now 42 patents involves in the ongoing legal brouhaha between Apple and Motorola.

Apple now alleges that Motorola infringes 24 of its patents (21 of them with Android-based phones, the remaining 3 with set-top boxes and DVRs), while Motorola previously asserted 18 patents against a variety of Apple products (mostly but not exclusively iPhone, iPad and iPod), reports “Foss Patents” (http://fosspatents.blogspot.com/2010/12/apple-vs-motorola-now-42-patents-in.html).

Litigation between the two companies takes place in several different federal courts — primarily the Western District of Wisconsin and the Southern District of Florida — as well as before the US International Trade Commission (ITC), the article adds. Last week it was announced that Apple’s patent claims against Motorola will be reviewed by the ITC, which could issue an order banning Motorola phones from the U.S. The ITC will determine if Motorola is infringing Apple patents and whether it should rule to block U.S. imports of Motorola phones made overseas that run on Google’s Android operating system.

Last month Apple sued Motorola, alleging that the company’s smartphone lineup and the operating software it uses infringe on the iPhone-maker’s intellectual property. The two lawsuits came after Motorola sued Apple in October for patent infringement. Motorola claims that Apple’s iPhone, iPad, iPod touch and certain Mac computers infringe Motorola patents.

Overall, Motorola Mobility’s three complaints include 18 patents, which the company says relates to early-stage innovations developed by Motorola in technology areas found on many of Apple’s core products and associated services, including MobileMe and the Apple App Store. The Motorola patents include wireless communication technologies, such as WCDMA (3G), GPRS, 802.11 and antenna design, and key smartphone technologies including wireless email, proximity sensing, software application management, location-based services and multi-device synchronization.

Motorola Mobility has requested that the ITC commence an investigation into Apple’s use of Motorola’s patents and, among other things, issue an Exclusion Order barring Apple’s importation of “infringing” products, prohibiting further sales of infringing products that have already been imported, and halting the marketing, advertising, demonstration and warehousing of inventory for distribution and use of such imported products in the United States. In the District Court actions, Motorola Mobility has requested that Apple cease using Motorola’s patented technology and provide compensation for Apple’s past infringement.