By Mike Scarcella

(Reuters) - The judge who could rewrite the future of Google's app business is a competition law expert who once defended technology companies and other defendants in antitrust cases.

U.S. District Judge James Donato in San Francisco will decide what changes to impose on Alphabet's Google Play store, after a jury on Monday agreed with "Fortnite" maker Epic Games that Google illegally barred competing Android app stores and forced developers to use its payment system for in-app transactions.

Donato, a 2014 Obama appointee, will consider arguments from both sides next month, when Epic is expected to propose ways to undo Google's alleged monopoly.

Donato said near the end of the month-long trial that there was "more than enough evidence" for jurors to rule for Epic.