I first caught this story on WGN Chicago. A reporter got a tip that some of the workers in the Detroit plant[ I think it was Detroit] were drinking and smoking pot on their lunch break, and sure enough, they got caught on camera.
http://www.msnbc.msn.com/id/39321757/ns/business-autos/
http://www.msnbc.msn.com/id/39321757/ns/business-autos/