Story highlights Paul Callan: With pardon, Trump has rewarded Arpaio for trashing the Constitution, and slapped federal judiciary in the face

Callan: History and the voters will judge harshly Trump's gift to the law-breaking and unrepentant ex-sheriff

Paul Callan is a CNN legal analyst, a former New York homicide prosecutor and currently is counsel at the New York law firm of Edelman & Edelman PC, focusing on wrongful conviction and civil rights cases. Follow him on Twitter @paulcallan. The opinions expressed in this commentary are his own.

(CNN) President Trump swore an oath to uphold the Constitution, which requires him to "take care that the laws be faithfully executed."

Given the clarity of that instruction, it is truly bizarre that Trump would grant his first presidential pardon to Joe Arpaio, the controversial former sheriff of Maricopa County, Arizona, who is also a persistent and legendary violator of the legal and constitutional rights of Latino visitors, residents and citizens.

After two respected federal judges struggled to compel the publicity-hungry sheriff to obey the law, first by holding him in civil contempt and later convicting him of criminal contempt, the President has chosen a different route. He has rewarded the ex-sheriff for trashing the Constitution, and has once again slapped the federal judiciary in the face.

Other presidents are remembered for their courage in upholding and enforcing the lawful orders of federal courts. John F. Kennedy's proclamation in 1963 forced the Alabama governor, George Wallace, to comply with federal court orders permitting black students to register at the University of Alabama. Kennedy then met with his brother, Attorney General Robert Kennedy, to find other ways to help the federal courts enforce desegregation orders in Alabama.

When Wallace continued his defiance, Kennedy threatened to federalize the Alabama National Guard. Kennedy undoubtedly infuriated many in Alabama, but he earned a place in history and the respect of the nation for his courage in supporting the Constitution, the federal courts and the rule of law.