A US appeals court on Friday ruled that Motorola Mobility cannot enforce an injunction in Germany that could have prevented Microsoft from selling some products, including Windows and the Xbox 360, in that country. The ruling was widely expected and serves as just the latest step in a long-running series of legal milestones between the two firms and others in the mobile industry.

“This case is a private dispute under Washington state contract law between two US corporations,” the ruling explains, noting that Microsoft’s breach-of-contract lawsuit against Motorola Mobility in this country precludes any international legal relief efforts. Thus, Motorola’s sales injunction attempt in Germany is moot.

Google-owned Motorola Mobility had secured a legal victory against Microsoft in May when the software giant was found by a court in Germany to be infringing on Motorola patents related to video-playback capabilities in Windows and the Xbox 360. Although this could have otherwise resulted in Microsoft being forced to take its products off the German market until the matter was resolved, a previous US district court ruling precluded that outcome.

Last week’s ruling from the 9th US Circuit Court of Appeals in San Francisco upholds the previous US district court ruling. In that ruling, US District Judge James Robart said that the patents in this case are of the so-called standards-essential variety and thus can’t be wielded against another firm to acquire a sales injunction. Microsoft had argued to the court that Motorola’s protection of this kind of patent is illegal.

Though Motorola is attacking core Microsoft products like Windows and the Xbox, the real battle here is in the mobile market. After securing patent-licensing agreements from most makers of Android-based handsets and other devices, Microsoft has aggressively pursued the few holdouts, one of which is Motorola. Also in May, Microsoft won a legal victory against Motorola Mobility in which a regional court in Germany ruled that the mobile company’s Android-based handsets do infringe on Microsoft mobile patents.

Not coincidentally, European antitrust officials are separately investigating whether Motorola Mobility has tried to overcharge both Apple and Microsoft for the standards-essential patents at the heart of this case.