James Madison frequently remarked that “all just and free government derives from social compact.” Indeed, this is the basis of government in the Declaration of Independence, which specifies that the “just powers” of government derive from the “consent of the governed.” Because “all men are created equal”—because, that is, no one by nature has the right to rule anyone else—the only legitimate source of rule is the consent of those who are to be ruled, and the only legitimate reason for consent is for the “safety and happiness” of those who agree to be ruled. In agreeing to join civil society, each individual freely accepts the obligation to protect the rights of fellow citizens in return for the protection of his own rights. The “just powers” of government are thus directed to the equal protection of the equal rights of those who consent to be governed. Equal rights—life, liberty, and the pursuit of happiness—derive from “the laws of nature and of nature’s God.” Equal protection of those rights is the very definition of the rule of law. Equal protection of the laws is thus intrinsic both to the social compact and to the Constitution.
Equal protection under the law, what a concept! There was a time in my life when if a case was brought before a judge the arresting officer would be asked if the same charges were leveled against his or her mother, would they have arrested her? Had the officer said no, you would here a loud, "case dismissed" from the bench, and for good reason. You cannot enforce a law against one citizen and not another. That's were the concept of equal justice under the law applies. The law applies to you, as it does to me.
Enter our tax code...
The tax code is a law. It is unfair and unjust to tax one citizen at a different rate than another! Suppose we decided everyone with red hair should pay extra? What if all right handed people had a higher percentage levied against them? Taxes were designed to fund the government, not to punish it's citizens. When will Washington ever get this concept?