Common law is basically whataboutism. Whataboutism isn't inherently bad, it's not always a deflection. It is reasonable to expect similar treatment for similar actions. If anything, reciprocity is one of the very foundations of society and of our justice system. You can't really discuss a lawsuits without talking about precedent, it's inherent to the discussion

(In a way it's amazing how shouting whataboutism is now more often used to deflect or excuse double standards and unfairness than whatboutism itself.)