The unconstitutional part of the constitution
Trump found it
tl;dr: Pardoning Arpaio is unconstitutional because it directly causes future 5a violations, and 5a is higher law than pardon power.
The US constitution states:
“Representatives … shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons.”
Of course, as we all know, that “three-fifths” was a slavery bonus; not content with stealing the labor, liberty, and children of their slaves, southern whites wanted to steal their voting power as well, and northerners “compromised” by giving southerners “only” 60% of that stolen power.
That clause is still inked onto the parchment of the constitution, but since the fourteenth amendment, it’s unconstitutional. Nobody today is counted as 3/5 for the purposes of somebody else’s vote. [Children, non-citizens, and (in states like Florida) felons still have their voting power appropriated by others, but that’s another story.]
You already knew all of that. But what does it have to do with Trump?
Trump just pardoned Joe Arpaio for his criminal contempt for constitutional rights. The pardon power is in the base text of the constitution; the rights in question are in the fifth amendment. Here are the two texts:
The President … shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment.
and:
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
Arpaio’s crime was to ignore the fifth amendment, even after being ordered to stop by a judge. He routinely imprisoned people who were suspected of no crime (since immigration offenses are civil, not criminal; and anyway, Arpaio had no jurisdiction to enforce immigration law); and continued to do so for over 5 years after being ordered to stop.

In these actions, Arpaio was much worse than a common criminal. He was precisely the kind of monster that the Constitution was written to prevent: a tyrant backed by the power of the state yet unrestrained by the rule of law. Consider what another founding document, the Declaration of Independence, would say about Arpaio:
He has refused his assent to laws, the most wholesome and necessary for the public good.
…
He has endeavored to prevent the population of these states; for that purpose obstructing the laws for naturalization of foreigners; refusing to pass others to encourage their migration hither, …
He has obstructed the administration of justice, by refusing his assent to laws for establishing judiciary powers
…
He has affected to render the military independent of and superior to civil power.
…
For depriving us in many cases, of the benefits of trial by jury:
…
He has abdicated government here, by declaring us out of his protection and waging war against us.
Pardoning Arpaio is totally unlike a normal use of presidential pardon powers, in many ways. Some of those ways are troubling but present no constitutional issues. For instance, Trump made a mockery of the usual procedures for reviewing a case prior to pardon, and Arpaio, though undisputedly guilty, has never expressed remorse for his crimes.
But the key difference, from a constitutional point of view, is that the fifth amendment is a guarantee of rights, not a criminal law. If those rights cannot be protected, they literally do not exist. The injunction was the means of protecting those rights, and thus had the full force of the 5th amendment, which is posterior and thus superior to the base text of the constitution. Arpaio’s crime was not merely a pardonable “Offense against the United States”, it was an unpardonable offense against the constitution itself.
Trump’s pardon of Arpaio was rash, racist, un-American, and contemptuous of the rule of law. But all that’s just an average Friday for Trump. The difference is, this time it’s unconstitutional.
