The high stake game between Microsoft and Motorola has taken another twist with U.S. International Trade Commission Judge Theodore Essex delaying a key ruling for another 4 days.The case is the first real test of Microsoft’s claim that it effectively owns large parts of the Android OS through patents, and a win would bar certain Android phones and the Xoom tablet from being sold.

The new date for a decision, which was due today, is December 20th.

Most of the specific model phones named in the ITC complaint, which was launched in August, are either now discontinued or on the way out, but a victory could possibly put the entire future of Android in doubt.

Motorola claims that the Microsoft Windows Phone violates a number of Motorola patents. Motorola Mobility is currently in the process of being acquired by Google, which could change the nature of the dispute and make Google directly liable should Microsoft prevail in both cases.

Microsoft has encountered considerable success in pressuring handset manufacturers into licensing Microsoft patents it claims are infringed in Android, but the claim has not been tested in court.