The platform holder will be pursing their own "enforcement action" if they detect illegal copies being played over Xbox Live, such as "account and console bans." Judgment is a prequel to the trilogy.
The official date for Gears of War: Judgement to be in the shops is March 22nd. Microsoft threatened similar 'vigorous action' against Halo 4 piracy when it leaked.
"We are aware of isolated cases in which Gears of War: Judgment content has been propped on the web and are working closely with our security teams and law enforcement to address the situation immediately," said a Microsoft statement. "Consumers should be aware that piracy is illegal and we take vigorous action against illegal activity related to our products and services." They're more than aware as pirated copies require modified consoles - it's no accident.
Polish developer People Can Fly are behind Gears of War: Judgment. The studio was bought by Epic Games and given work on the IP after their own shooter - Bulletstorm - failed to inspire much commercial success.