Unauthorized use of a machine, including theft, often results in accidents because the person using the machine usually has not been properly trained. Locking up the machine, keeping keys off the premises, or securing the machine in a non-accessible area easily guards against unauthorized use.
Unauthorized usage cases can show the extremes of litigation in the area of lifts. In one case, the son of the owner of a rental yard took his girlfriend up on a scissors lift late at night without properly extending the outriggers. One thing led to another up on that platform, and the lift rocked so that it overturned. One of the parties suggested a decal warning against such activities (a red circle with a slash over a picture depicting the activity in which the young couple was engaged) be added to the machine. The proposed decal was never produced. The matter was resolved based upon the fact that the young man was an experienced operator who should have known better than to operate the lift without outriggers.
Another case involved several men who decided to entertain some children by taking them up in a stolen man lift. In injury and product defect cases, obtaining a lift though illegal means does not affect the way a case is presented. The best defense in these cases may be that because of the unauthorized use (and in cases of theft, hasty use, as well), the operators did not familiarize themselves with the machine, read the manual, or take safety precautions–no different than if the machines were legally obtained.