....The actual rule only has four noted exceptions. ...
I believe there has been a case or cases where the “existence of duty” was an allowable exception. However, IMO, it is limited because an “existence of care” is synonymous to “duty of care” which is one element of negligence. So, IMO, because subsequent measures are excluded to prove negligence, then the “existence of duty” should/must also be excluded.
IMO, MW will not be able to get the evidence of subsequent measures in but if argued in front the jury, even if the court declined his motion to introduce the subsequent measures, the jury has heard it and, as I stated before, jurors (even when properly instructed otherwise) could still likely consider it (not legally) as RCCL “admitting” the window design was flawed/needed to be changed and this may sway the verdict in favor of the plaintiff. JMO