US President Donald Trump has issued a mid-term pardon to divisive former Arizona Sheriff Joe Arpaio, in an intensely political – and controversial – decision touching on immigration policy, lingering tensions with the Obama administration, and the wider issue of using executive power to commute a sentence. The 85-year-old lawman who dubbed himself "America's toughest sheriff" courted controversy with his targeting of Hispanic immigrants, and was found guilty of criminal contempt in July in a case involving racial profiling.