A dominant firm like Google does not violate the law, however, merely because it occupies a monopoly market position. It must act in a manner that produces anticompetitive effects in the defined markets. [e.g., that harm consumers].Mozilla CEO testifying on behalf of Google (page 109 of MSJ transcript):
...consumers are choosing Google. We’re making search easy for them, and we added choice in a product in a way that no one else had or even thought of. We’re making it easy. ...
In response, the Justice Dept. is trying to exclude testimony about Google's quality. They seem to miss the irony that this makes them seem as if they are more concerned with Google's complaining competitors than their enthusiastic customers.
UDPATE: the judge ruled against the DOJ, in essence telling them they should be more concerned with what Google's customers are saying.