Section 411.320 - Circumstances under which defendant is liable(1) In any product liability action, a manufacturer shall be liable only for the personal injury, death or property damage that would have occurred if the product had been used in its original, unaltered and unmodified condition. For the purpose of this section, product alteration or modification shall include failure to observe routine care and maintenance, but shall not include ordinary wear and tear. This section shall apply to alterations or modifications made by any person or entity, except those made in accordance with specifications or instructions furnished by the manufacturer.(2) In any product liability action, if the plaintiff performed an unauthorized alteration or an unauthorized modification, and such alteration or modification was a substantial cause of the occurrence that caused injury or damage to the plaintiff, the defendant shall not be liable whether or not said defendant was at fault or the product was defective.(3) In any product liability action, if the plaintiff failed to exercise ordinary care in the circumstances in his use of the product, and such failure was a substantial cause of the occurrence that caused injury or damage to the plaintiff, the defendant shall not be liable whether or not said defendant was at fault or the product was defective.Effective:6/17/1978 Created 1978 Ky. Acts ch. 91, sec. 4, effective6/17/1978.