SAN FRANCISCO — The California Supreme Court appeared likely on Wednesday to shield manufacturers from liability in a case that could open up a new frontier in high-stakes asbestos litigation.

With asbestos companies long bankrupt, plaintiffs suing over asbestos-related illnesses have shifted their theories of liability to try to recover damages from the makers of equipment routinely used with products that contained deadly asbestos fibers. Defendants, however, say they can’t be held liable for how customers used their products years later.