What is not considered a common-law defense for an employer in a workplace injury lawsuit?

Proximate cause is not considered a common-law defense for an employer in a workplace injury lawsuit because it pertains to the relationship between the cause of an injury and the injury itself, rather than serving as a defense against liability. Proximate cause is used to establish whether the injuries sustained were a foreseeable result of the employer's actions or negligence but doesn't function as a defense to the employer's liability in the same way that the other options do.

Common-law defenses, like contributory negligence, assumption of risk, and comparative negligence, are specifically employed by employers to argue against liability claims by injured workers. For example, contributory negligence asserts that the injured party's own negligence contributed to the accident, potentially barring their claim. Assumption of risk involves the worker knowingly accepting the dangers associated with their job, which can negate employer liability. Comparative negligence, on the other hand, allows for a proportional attribution of fault to both the employer and the employee, which could limit the compensation to the injured worker based on their share of the blame. Hence, while proximate cause is relevant to establishing liability, it does not serve as a defense in the same capacity as the others listed.