An administrative law judge today issued an initial determination that Motorola Mobility is in violation of one of six Microsoft patents listed in a patent infringement suit filed by Microsoft against Motorola Mobility.

Microsoft had previously dropped two patents from its original case which included nine patents. Specifically, the judge determined that Motorola Mobility infringed on four claims of U.S. Patent No. 6,370,566, which is related to “generating meeting requests and group scheduling from a mobile device.”

The case will now go on to review by the ITC where a final decision is expected on the matter by April 20, 2011.

Scott Offer, senior vice president and general counsel of Motorola Mobility, said in a statement that his company was “pleased that the majority of the rulings were favorable to Motorola Mobility.”

Motorola Mobility maintains that Microsoft continues to infringe on its patent portfolio. The company has active patent infringement litigation and proceedings against Microsoft in a number of jurisdictions, including the U.S. International Trade Commission (ITC).