“They can, and have always been able to.”
I think they are required to actually go and hear the gospel at Mass, no matter their irregular or disordered situation.
Freegards
Yes. Assisting at Mass onSunday is everyone’s obligation, even those in “irregular situations” or, worse yet, mortal sin. Yes, those in mortal sin are still obliged to obey the laws which Christ teaches us through His Church.