The high court is scheduled to hear arguments in a special session starting at 9 a.m. ET (1300 GMT). The plaintiffs in the lawsuit, led by leaders of the Republican-controlled state legislature, contend that McAuliffe's April 22 order is unconstitutional since it is a blanket restoration of voting rights to felons.
Republicans criticized McAuliffe's move to grant felons access to the voting booth because many of those benefitted would have been minorities who tend to vote Democratic. Considering McAuliffe has been friends with the Clintons for years, his executive order appeared to have been made with the 2016 election in mind.
A report last week discovered that a few of the criminals on McAuliffe's voting list were fugitive sex offenders.