ITC Judge David Shaw said that Microsoft infringed four patents and did not infringe on a fifth in the complaint.
According to Reuters, it will be up to a full commission to review the judge's decision and issue a final ruling in August, but things are not looking good.
The patents in the complaint are for technology like wireless connections for the Xbox to the Internet and video compression to speed transmission.
Needless to say Motorola Mobility asked for the infringing devices to be barred from importation into the United States.
While it is unlikely that the Xbox will be withdrawn from sale in the US, it does mean that Vole might have to sling its hook over other patents it is trying to enforce against Google.
Microsoft said it would press on with the case saying it thinks that the commission will ultimately rule in its favour.
The ITC is a US trade panel that investigates patent infringement involving imported goods, and is a popular venue for patent lawsuits because it can bar the importation of infringing products and because its cases are ruled on quicker than normal courts.