"The last time a workprint copy of a high profile movie hit the web, a BitTorrent site got shutdown by the FBI and several people went to jail. A US citizen caught seeding a pre-release movie faces 5 years in jail..."
The above reference was from Operation D-Elite where it is believed that the pre-release of the new Star Wars movie set off the raids leading to "the subsequent jailing of several people including Scott McCausland, Grant Stanley, Sam Kuonen and Scott D. Harvanek..."
Currently, Lions Gate Entertainment faces 'workprint copies'--described as "a rough, unfinished form"--of its new horror film, Hostel: Part II. Tom Ortenberg, the Lions Gate President, commented that the pre-release is "...distressing and disappointing...but it will have no meaningful impact on the box office."
"…yet in the US, you can get 5 years in jail for it." Of course.