A successful Eugene product defect lawsuit must demonstrate that the product came into the possession of the injured person without having been previously modified. In other words, if you modify a product and that modification makes the product dangerous, then the manufacturer, seller, or lessor will have a strong defense against your lawsuit.
However, there are instances when consumer modifications are foreseeable, in which case the manufacturer may have to address these modifications with an appropriate warning. Also, manufacturers sometimes suggest modifications, and these can be what makes a product dangerous.