Court challenges to the phase-out of the program have now risen to the top court, whose justices will take stock of the issue during oral arguments
Policy change to affect about 800,000 undocumented immigrants currently shielded under DACA program
Any decision to wind down program would start clock on throwing previously undocumented immigrants
White House claims that DACA is illegal but deferred action is a widely accepted legal principle
Trump is expected to announce if he will end the Deferred Action for Childhood Arrivals programme