What social norms is Meursault breaking in Chapter 1 in the stranger?

Meursault is not grieving over his mother's death. This is against established societal traditions which dictate that one should grieve on death.

Explanation:

Meursault seems to be physiologically detached from the physical world. This is evident from his decision to not grieve on his mother's death.

The above decision went against the established societal norms. However, Meursault chose to be honest with his feelings. This act of Meursault's was interpreted as a cumulative threat by the society which branded him an outsider. His decision of pursuing such action cant be said immoral but amoral. This is due to his inability to differentiate between the good and the bad.