Basically, leftist morality is all about "fairness" and "caring". They care nothing about authority or loyalty. Leftists care nothing about obeying the Constitution since it is "authority."
Conservative morality includes not only fairness and caring, but also authority and loyalty. This gives conservatives more respect (usually anyway) for the rule of law and the constitution.
Johnathan Haidt's "The Righteous Mind" explains this very well.
Basically, leftist are morally incapable of giving a damn about the law or the Constitution. Hence, their continual support for illegal immigration, voter fraud, restrictions on free speech etc.