"Legal precedent" for litigation based upon liability, in the US? Are you kidding me? This is the country where major gunmakers get sued when a gun they manufactured is used in a crime, FFS! I don't know how things work up there in Canada, but down here in the States legal action based on liability is a way of life. Taking responsibility for one's own actions is a quaint fairy tale from another time and a "liability release" isn't worth the paper it's printed upon.

The fact that you ask for "engineering formulas" to back up what I've said tells me plainly that you have no idea what the hell you are talking about in that regard as well, so no further keystrokes will be wasted upon you.