In Robinson v Hooker, the Western District Court of Appeals held that the Workers Compensation Act did not extend its immunity to coworkers.  For two years, it appeared that there was an open season on co-employees in Missouri.  However, in Hansen v. Ritter, at least a part of the protection was restored when the Western District held that, while not "immune," co-employees did not owe a personal duty of care to provide a safe workplace for fellow employees.  Hansen involved to supervisors who were sued solely on the basis that they had failed to do certain things to provide a safe work environment. Consequently, the scope of protection provided by the "no duty" rule did not appear to be as broad as the pre-Hooker immunity cases.

Carmen appears to apply the "no duty" rule as broadly as the old immunity concept. In Carmen, a firefighter was sued by the widow of another firefighter for negligently backing over the fellow firefighter.  The plaintiff clearly alleged that defendant had operated the fire truck negligently and had failed to exercise the highest degree of care in the operation of the fire truck.  The court held that as a matter of law the defendant's conduct in backing the fire truck was subsumed in the employer's nondelegable duty to provide a safe place to work and, therefore, he owed no independent duty to the deceased. The court stated that in order to state a claim against a coworker, the plaintiff must allege "an affirmative act directed at a particular employee that places the co-employee's conduct outside the scope of the employer's non-deliverable duties."  Consequently, Carmen appears to expand the "no duty" concept to essentially the same scope as the prior immunity cases.