Elon Musk is testing the limits of legal and ethical restrictions on the role of special advisers in U.S. presidential administrations, according to some legal experts and lawmakers who oppose the billionaire's mission against what he deems wasteful government spending.

Elon Musk will work under President Donald Trump as a “special government employee,” designating Musk as an unpaid employee of the federal government with fewer restrictions than full-time employees, according to the White House, as Musk’s so-called Department Of Government Efficiency has involved itself in multiple federal agencies in recent days.