7.7 UNSEAWORTHINESS—CAUSATION DEFINED
The definition of causation for the plaintiff's unseaworthiness claim is different from that for the Jones Act negligence claim.
Unseaworthiness is a cause of injury or damage if it was a substantial factor in bringing about injury or damage.
A different test for causation applies to an unseaworthiness claim as compared to a Jones Act negligence claim. See Ribitzki v. Canmar Reading & Bates, Ltd. P’ship, 111 F.3d 658, 665 (9th Cir.1997) (causation is established for unseaworthiness claim by showing condition was "substantial factor" in causing injury). When both Jones Act negligence and unseaworthiness claims exist, the court should instruct on the causal requirements for each. See Lies v. Farrell Lines, 641 F.2d 765, 769 n.7 (9th Cir.1981).