NAL, Contracts can't offer full protection from liability, that is a layman myth. What it can do is insulate the party from some level of liability. This is usually calculated as a percentage (the amount of which is determined in different regions different ways through years of previous judgements). Basically, it can reduce your percentage of liability, which in different states can offer different things. In some states, it can mitigate claimed damages, in others it can 'nearly' void liability, but it depends on how 'cause' is defined (in some states it has to be 100% in others 50-50 is enough to seek damages).