P, a long-haul trucker was hauling a forty-eight-foot Super Hopper trailer manufactured by D. The trailer is a standard open-top, twin hopper trailer, that is loaded from above through use of a downspout or other device and is emptied through two openings on its bottom. A tarp is rolled over the top to protect its contents. A ladder and an observation platform are attached to the front and rear of the trailer to allow the operator to view its contents. P backed his trailer under the downspout at the Martin fertilizer plant and yelled to a Martin employee to begin loading. To prevent fertilizer from being blown away during the loading process, P attempted to lower the downspout by using a rope attached to it. P could not get it to work. He had previously complained to Martin employees about problems lowering the downspout, but he did not do so again that morning. P climbed atop the trailer without using the ladder as he had always done in the past and attempted to lower the downspout by hand while standing on the trailer's top rail. This top rail is also the top of the trailer's side wall. It is made of extruded aluminum, is between 5 and 5.66 inches wide, and is nine-and-a-half feet above the ground. A gust of wind hit him from the back, causing him to fall. P fractured his legs, broke his ankles, and ruptured an Achilles tendon and was wheelchair bound for 6 months. P still has difficulty walking and standing. P sued asserted a premises liability against Martin. P also asserted an action for marketing, manufacturing, and design defects, misrepresentation, and breach of warranty against D; The warning labels on the Super Hopper trailer were insufficient to warn him of the danger of climbing on top of the trailer, and that the trailer contained two design defects: The top two rungs of the ladders attached to the front and rear of the trailer allow a person to climb atop the trailer; and The top rail of the trailer is too narrow and slippery and contains too many tripping hazards for a person to walk safely along it. P's expert witness, proposed three design changes to remedy the issues with D. D moved for a no-evidence summary judgment which the trial court granted. The court of appeals concluded that there was 'some evidence upon which reasonable factfinders could disagree as to whether the trailer's design was both unreasonably dangerous and a cause of P's fall.' It reversed, and D appealed.