Over the weekend pictures and forum threads started to illustrate that players had somehow gotten their hands on early copies of Halo 4 - which isn't set for release until November 6th. Microsoft was obviously not very pleased with this news and promised that it would conduct an investigation into the early leaks of the game and would do so in conjunction with law enforcement.
In addition to that Microsoft also said that it will permanently ban any Xbox Live users who have been found to be playing the game on the service early. Obviously if Microsoft can find these individuals and ban them, chances are they can expect to be visited by law enforcement as well. Since the version of Halo 4 being played early is a copy it requires the use of a modded Xbox 360 console in order to play as well.
The early indications that Microsoft was doing this are detailed in a screen grab of an email it is sending to those naughty Xbox Live users caught with their hands in the Halo 4 cookie jar. From the email:
"This email is to notify you that your Xbox Live privileges have been permanently suspended due to illegitimate prerelease title play," the warning email reads. "Because your conduct is in violation, the Xbox Live Enforcement Team has issued a permanent suspension. Your Xbox Live privileges will not be reinstated."
You can see a screen capture of that email on MCV.