The patent refers to “a computer system for identifying local resources”, according to patent expert Florian Mueller.
Google has been unable to convince the court that the patent does not apply to the technology used in its mapping services.
Microsoft is seeking – and very likely to obtain, according to Mr Mueller – an injunction against the Google Maps service.
In order to comply with the likely injunction, Google would have to disable Google Maps from all computers using a German IP address.
It would also have to stop shipping the Google Maps Android app and only distribute web browsers in Germany only if they used internet filters to block access to Google Maps.
Microsoft originally only sued Motorola Mobility and its German subsidiary over the distribution of the Android app. It only engaged Google as a defendant after Motorola executives denied knowledge of how Google Map servers operated.
In order to maintain the service, Google would have to pay royalties to Microsoft for the Microsoft intellectual property that it uses for its maps. Samsung, HTC, LG and other makers of Android devices have already recognised the patent applying to the Microsoft technology and taken out licensing agreement.
The report comes as Google is accused of “arrogance”in the UK after it apparently ignored requests for privacy and published photographs of their homes from its Street View service.
More than half a dozen homeowners in Surrey asked the web giant not to post images of their properties online after it introduced Street View to Britain in 2009 over fears they could be used by burglars. Google duly blurred the pictures, only to republish fresh, unblurred ones later.
In separate news, it has emerged in a company email that Motorola Mobility is to cut more than 10 per cent of its workforce as Google moves to streamline its mobile phone business.
Google bought the loss-making Motorola for $12.5bn last year, its largest ever acquisition.